Eric Lee / smarc-fsl-linux-kernel

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Commit ef8ff89b58546055e238c3b521f83b440dfe8ef2

Authored by Michal Marek
1 parent 2d74b2c62c
Exists in master and in 39 other branches 8mp-imx_5.4.70_2.3.0, 8qm-imx_5.4.70_2.3.0, emb_imx_lf-5.15.y, emb_lf-6.1.y, imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, imx_4.1.15_1.0.0_ga, pitx_8mp_lf-5.10.y, rt-smarc-imx_4.1.15_1.0.0_ga, rt_linux_5.15.71, smarc-8m-android-11.0.0_2.0.0, smarc-imx6_4.14.98_2.0.0_ga, smarc-imx6_4.9.88_2.0.0_ga, smarc-imx7_4.14.98_2.0.0_ga, smarc-imx7_4.9.11_1.0.0_ga, smarc-imx7_4.9.88_2.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-imx_4.1.15_1.0.0_ga, smarc-imx_4.9.11_1.0.0_ga, smarc-imx_4.9.51_imx8m_ga, smarc-imx_4.9.88_2.0.0_ga, smarc-m6.0.1_2.1.0-ga, smarc-n7.1.2_2.0.0-ga, smarc-rel_imx_4.1.15_1.2.0_ga, smarc_8m_00d0_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.14.78_1.0.0_ga, smarc_8m_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.19.35_1.1.0, smarc_8mm_imx_4.14.78_1.0.0_ga, smarc_8mm_imx_4.14.98_2.0.0_ga, smarc_8mm_imx_4.19.35_1.1.0, smarc_8mm_imx_5.4.24_2.1.0, smarc_8mp_lf-5.10.y, smarc_8mq_imx_5.4.24_2.1.0, smarc_8mq_lf-5.10.y, smarc_imx_lf-5.15.y

kbuild: Really don't clean bounds.h and asm-offsets.h 

Commit 7d3cc8b tried to keep bounds.h and asm-offsets.h during make
clean by filtering these out of $(clean-files), but they are listed in
$(targets) and $(always) and thus removed automatically. Introduce a new
$(no-clean-files) variable to really skip such files in Makefile.clean.

Signed-off-by: Michal Marek <mmarek@suse.cz>

Showing 3 changed files with 11 additions and 2 deletions Inline Diff

Documentation/kbuild/makefiles.txt
Diff comments   View file @ ef8ff89
1 Linux Kernel Makefiles 1 Linux Kernel Makefiles
2 2
3 This document describes the Linux kernel Makefiles. 3 This document describes the Linux kernel Makefiles.
4 4
5 === Table of Contents 5 === Table of Contents
6 6
7 === 1 Overview 7 === 1 Overview
8 === 2 Who does what 8 === 2 Who does what
9 === 3 The kbuild files 9 === 3 The kbuild files
10 --- 3.1 Goal definitions 10 --- 3.1 Goal definitions
11 --- 3.2 Built-in object goals - obj-y 11 --- 3.2 Built-in object goals - obj-y
12 --- 3.3 Loadable module goals - obj-m 12 --- 3.3 Loadable module goals - obj-m
13 --- 3.4 Objects which export symbols 13 --- 3.4 Objects which export symbols
14 --- 3.5 Library file goals - lib-y 14 --- 3.5 Library file goals - lib-y
15 --- 3.6 Descending down in directories 15 --- 3.6 Descending down in directories
16 --- 3.7 Compilation flags 16 --- 3.7 Compilation flags
17 --- 3.8 Command line dependency 17 --- 3.8 Command line dependency
18 --- 3.9 Dependency tracking 18 --- 3.9 Dependency tracking
19 --- 3.10 Special Rules 19 --- 3.10 Special Rules
20 --- 3.11 $(CC) support functions 20 --- 3.11 $(CC) support functions
21 --- 3.12 $(LD) support functions 21 --- 3.12 $(LD) support functions
22 22
23 === 4 Host Program support 23 === 4 Host Program support
24 --- 4.1 Simple Host Program 24 --- 4.1 Simple Host Program
25 --- 4.2 Composite Host Programs 25 --- 4.2 Composite Host Programs
26 --- 4.3 Defining shared libraries 26 --- 4.3 Defining shared libraries
27 --- 4.4 Using C++ for host programs 27 --- 4.4 Using C++ for host programs
28 --- 4.5 Controlling compiler options for host programs 28 --- 4.5 Controlling compiler options for host programs
29 --- 4.6 When host programs are actually built 29 --- 4.6 When host programs are actually built
30 --- 4.7 Using hostprogs-$(CONFIG_FOO) 30 --- 4.7 Using hostprogs-$(CONFIG_FOO)
31 31
32 === 5 Kbuild clean infrastructure 32 === 5 Kbuild clean infrastructure
33 33
34 === 6 Architecture Makefiles 34 === 6 Architecture Makefiles
35 --- 6.1 Set variables to tweak the build to the architecture 35 --- 6.1 Set variables to tweak the build to the architecture
36 --- 6.2 Add prerequisites to archprepare: 36 --- 6.2 Add prerequisites to archprepare:
37 --- 6.3 List directories to visit when descending 37 --- 6.3 List directories to visit when descending
38 --- 6.4 Architecture-specific boot images 38 --- 6.4 Architecture-specific boot images
39 --- 6.5 Building non-kbuild targets 39 --- 6.5 Building non-kbuild targets
40 --- 6.6 Commands useful for building a boot image 40 --- 6.6 Commands useful for building a boot image
41 --- 6.7 Custom kbuild commands 41 --- 6.7 Custom kbuild commands
42 --- 6.8 Preprocessing linker scripts 42 --- 6.8 Preprocessing linker scripts
43 43
44 === 7 Kbuild syntax for exported headers 44 === 7 Kbuild syntax for exported headers
45 --- 7.1 header-y 45 --- 7.1 header-y
46 --- 7.2 objhdr-y 46 --- 7.2 objhdr-y
47 --- 7.3 destination-y 47 --- 7.3 destination-y
48 --- 7.4 unifdef-y (deprecated) 48 --- 7.4 unifdef-y (deprecated)
49 49
50 === 8 Kbuild Variables 50 === 8 Kbuild Variables
51 === 9 Makefile language 51 === 9 Makefile language
52 === 10 Credits 52 === 10 Credits
53 === 11 TODO 53 === 11 TODO
54 54
55 === 1 Overview 55 === 1 Overview
56 56
57 The Makefiles have five parts: 57 The Makefiles have five parts:
58 58
59 Makefile the top Makefile. 59 Makefile the top Makefile.
60 .config the kernel configuration file. 60 .config the kernel configuration file.
61 arch/$(ARCH)/Makefile the arch Makefile. 61 arch/$(ARCH)/Makefile the arch Makefile.
62 scripts/Makefile.* common rules etc. for all kbuild Makefiles. 62 scripts/Makefile.* common rules etc. for all kbuild Makefiles.
63 kbuild Makefiles there are about 500 of these. 63 kbuild Makefiles there are about 500 of these.
64 64
65 The top Makefile reads the .config file, which comes from the kernel 65 The top Makefile reads the .config file, which comes from the kernel
66 configuration process. 66 configuration process.
67 67
68 The top Makefile is responsible for building two major products: vmlinux 68 The top Makefile is responsible for building two major products: vmlinux
69 (the resident kernel image) and modules (any module files). 69 (the resident kernel image) and modules (any module files).
70 It builds these goals by recursively descending into the subdirectories of 70 It builds these goals by recursively descending into the subdirectories of
71 the kernel source tree. 71 the kernel source tree.
72 The list of subdirectories which are visited depends upon the kernel 72 The list of subdirectories which are visited depends upon the kernel
73 configuration. The top Makefile textually includes an arch Makefile 73 configuration. The top Makefile textually includes an arch Makefile
74 with the name arch/$(ARCH)/Makefile. The arch Makefile supplies 74 with the name arch/$(ARCH)/Makefile. The arch Makefile supplies
75 architecture-specific information to the top Makefile. 75 architecture-specific information to the top Makefile.
76 76
77 Each subdirectory has a kbuild Makefile which carries out the commands 77 Each subdirectory has a kbuild Makefile which carries out the commands
78 passed down from above. The kbuild Makefile uses information from the 78 passed down from above. The kbuild Makefile uses information from the
79 .config file to construct various file lists used by kbuild to build 79 .config file to construct various file lists used by kbuild to build
80 any built-in or modular targets. 80 any built-in or modular targets.
81 81
82 scripts/Makefile.* contains all the definitions/rules etc. that 82 scripts/Makefile.* contains all the definitions/rules etc. that
83 are used to build the kernel based on the kbuild makefiles. 83 are used to build the kernel based on the kbuild makefiles.
84 84
85 85
86 === 2 Who does what 86 === 2 Who does what
87 87
88 People have four different relationships with the kernel Makefiles. 88 People have four different relationships with the kernel Makefiles.
89 89
90 *Users* are people who build kernels. These people type commands such as 90 *Users* are people who build kernels. These people type commands such as
91 "make menuconfig" or "make". They usually do not read or edit 91 "make menuconfig" or "make". They usually do not read or edit
92 any kernel Makefiles (or any other source files). 92 any kernel Makefiles (or any other source files).
93 93
94 *Normal developers* are people who work on features such as device 94 *Normal developers* are people who work on features such as device
95 drivers, file systems, and network protocols. These people need to 95 drivers, file systems, and network protocols. These people need to
96 maintain the kbuild Makefiles for the subsystem they are 96 maintain the kbuild Makefiles for the subsystem they are
97 working on. In order to do this effectively, they need some overall 97 working on. In order to do this effectively, they need some overall
98 knowledge about the kernel Makefiles, plus detailed knowledge about the 98 knowledge about the kernel Makefiles, plus detailed knowledge about the
99 public interface for kbuild. 99 public interface for kbuild.
100 100
101 *Arch developers* are people who work on an entire architecture, such 101 *Arch developers* are people who work on an entire architecture, such
102 as sparc or ia64. Arch developers need to know about the arch Makefile 102 as sparc or ia64. Arch developers need to know about the arch Makefile
103 as well as kbuild Makefiles. 103 as well as kbuild Makefiles.
104 104
105 *Kbuild developers* are people who work on the kernel build system itself. 105 *Kbuild developers* are people who work on the kernel build system itself.
106 These people need to know about all aspects of the kernel Makefiles. 106 These people need to know about all aspects of the kernel Makefiles.
107 107
108 This document is aimed towards normal developers and arch developers. 108 This document is aimed towards normal developers and arch developers.
109 109
110 110
111 === 3 The kbuild files 111 === 3 The kbuild files
112 112
113 Most Makefiles within the kernel are kbuild Makefiles that use the 113 Most Makefiles within the kernel are kbuild Makefiles that use the
114 kbuild infrastructure. This chapter introduces the syntax used in the 114 kbuild infrastructure. This chapter introduces the syntax used in the
115 kbuild makefiles. 115 kbuild makefiles.
116 The preferred name for the kbuild files are 'Makefile' but 'Kbuild' can 116 The preferred name for the kbuild files are 'Makefile' but 'Kbuild' can
117 be used and if both a 'Makefile' and a 'Kbuild' file exists, then the 'Kbuild' 117 be used and if both a 'Makefile' and a 'Kbuild' file exists, then the 'Kbuild'
118 file will be used. 118 file will be used.
119 119
120 Section 3.1 "Goal definitions" is a quick intro, further chapters provide 120 Section 3.1 "Goal definitions" is a quick intro, further chapters provide
121 more details, with real examples. 121 more details, with real examples.
122 122
123 --- 3.1 Goal definitions 123 --- 3.1 Goal definitions
124 124
125 Goal definitions are the main part (heart) of the kbuild Makefile. 125 Goal definitions are the main part (heart) of the kbuild Makefile.
126 These lines define the files to be built, any special compilation 126 These lines define the files to be built, any special compilation
127 options, and any subdirectories to be entered recursively. 127 options, and any subdirectories to be entered recursively.
128 128
129 The most simple kbuild makefile contains one line: 129 The most simple kbuild makefile contains one line:
130 130
131 Example: 131 Example:
132 obj-y += foo.o 132 obj-y += foo.o
133 133
134 This tells kbuild that there is one object in that directory, named 134 This tells kbuild that there is one object in that directory, named
135 foo.o. foo.o will be built from foo.c or foo.S. 135 foo.o. foo.o will be built from foo.c or foo.S.
136 136
137 If foo.o shall be built as a module, the variable obj-m is used. 137 If foo.o shall be built as a module, the variable obj-m is used.
138 Therefore the following pattern is often used: 138 Therefore the following pattern is often used:
139 139
140 Example: 140 Example:
141 obj-$(CONFIG_FOO) += foo.o 141 obj-$(CONFIG_FOO) += foo.o
142 142
143 $(CONFIG_FOO) evaluates to either y (for built-in) or m (for module). 143 $(CONFIG_FOO) evaluates to either y (for built-in) or m (for module).
144 If CONFIG_FOO is neither y nor m, then the file will not be compiled 144 If CONFIG_FOO is neither y nor m, then the file will not be compiled
145 nor linked. 145 nor linked.
146 146
147 --- 3.2 Built-in object goals - obj-y 147 --- 3.2 Built-in object goals - obj-y
148 148
149 The kbuild Makefile specifies object files for vmlinux 149 The kbuild Makefile specifies object files for vmlinux
150 in the $(obj-y) lists. These lists depend on the kernel 150 in the $(obj-y) lists. These lists depend on the kernel
151 configuration. 151 configuration.
152 152
153 Kbuild compiles all the $(obj-y) files. It then calls 153 Kbuild compiles all the $(obj-y) files. It then calls
154 "$(LD) -r" to merge these files into one built-in.o file. 154 "$(LD) -r" to merge these files into one built-in.o file.
155 built-in.o is later linked into vmlinux by the parent Makefile. 155 built-in.o is later linked into vmlinux by the parent Makefile.
156 156
157 The order of files in $(obj-y) is significant. Duplicates in 157 The order of files in $(obj-y) is significant. Duplicates in
158 the lists are allowed: the first instance will be linked into 158 the lists are allowed: the first instance will be linked into
159 built-in.o and succeeding instances will be ignored. 159 built-in.o and succeeding instances will be ignored.
160 160
161 Link order is significant, because certain functions 161 Link order is significant, because certain functions
162 (module_init() / __initcall) will be called during boot in the 162 (module_init() / __initcall) will be called during boot in the
163 order they appear. So keep in mind that changing the link 163 order they appear. So keep in mind that changing the link
164 order may e.g. change the order in which your SCSI 164 order may e.g. change the order in which your SCSI
165 controllers are detected, and thus your disks are renumbered. 165 controllers are detected, and thus your disks are renumbered.
166 166
167 Example: 167 Example:
168 #drivers/isdn/i4l/Makefile 168 #drivers/isdn/i4l/Makefile
169 # Makefile for the kernel ISDN subsystem and device drivers. 169 # Makefile for the kernel ISDN subsystem and device drivers.
170 # Each configuration option enables a list of files. 170 # Each configuration option enables a list of files.
171 obj-$(CONFIG_ISDN) += isdn.o 171 obj-$(CONFIG_ISDN) += isdn.o
172 obj-$(CONFIG_ISDN_PPP_BSDCOMP) += isdn_bsdcomp.o 172 obj-$(CONFIG_ISDN_PPP_BSDCOMP) += isdn_bsdcomp.o
173 173
174 --- 3.3 Loadable module goals - obj-m 174 --- 3.3 Loadable module goals - obj-m
175 175
176 $(obj-m) specify object files which are built as loadable 176 $(obj-m) specify object files which are built as loadable
177 kernel modules. 177 kernel modules.
178 178
179 A module may be built from one source file or several source 179 A module may be built from one source file or several source
180 files. In the case of one source file, the kbuild makefile 180 files. In the case of one source file, the kbuild makefile
181 simply adds the file to $(obj-m). 181 simply adds the file to $(obj-m).
182 182
183 Example: 183 Example:
184 #drivers/isdn/i4l/Makefile 184 #drivers/isdn/i4l/Makefile
185 obj-$(CONFIG_ISDN_PPP_BSDCOMP) += isdn_bsdcomp.o 185 obj-$(CONFIG_ISDN_PPP_BSDCOMP) += isdn_bsdcomp.o
186 186
187 Note: In this example $(CONFIG_ISDN_PPP_BSDCOMP) evaluates to 'm' 187 Note: In this example $(CONFIG_ISDN_PPP_BSDCOMP) evaluates to 'm'
188 188
189 If a kernel module is built from several source files, you specify 189 If a kernel module is built from several source files, you specify
190 that you want to build a module in the same way as above. 190 that you want to build a module in the same way as above.
191 191
192 Kbuild needs to know which the parts that you want to build your 192 Kbuild needs to know which the parts that you want to build your
193 module from, so you have to tell it by setting an 193 module from, so you have to tell it by setting an
194 $(<module_name>-objs) variable. 194 $(<module_name>-objs) variable.
195 195
196 Example: 196 Example:
197 #drivers/isdn/i4l/Makefile 197 #drivers/isdn/i4l/Makefile
198 obj-$(CONFIG_ISDN) += isdn.o 198 obj-$(CONFIG_ISDN) += isdn.o
199 isdn-objs := isdn_net_lib.o isdn_v110.o isdn_common.o 199 isdn-objs := isdn_net_lib.o isdn_v110.o isdn_common.o
200 200
201 In this example, the module name will be isdn.o. Kbuild will 201 In this example, the module name will be isdn.o. Kbuild will
202 compile the objects listed in $(isdn-objs) and then run 202 compile the objects listed in $(isdn-objs) and then run
203 "$(LD) -r" on the list of these files to generate isdn.o. 203 "$(LD) -r" on the list of these files to generate isdn.o.
204 204
205 Kbuild recognises objects used for composite objects by the suffix 205 Kbuild recognises objects used for composite objects by the suffix
206 -objs, and the suffix -y. This allows the Makefiles to use 206 -objs, and the suffix -y. This allows the Makefiles to use
207 the value of a CONFIG_ symbol to determine if an object is part 207 the value of a CONFIG_ symbol to determine if an object is part
208 of a composite object. 208 of a composite object.
209 209
210 Example: 210 Example:
211 #fs/ext2/Makefile 211 #fs/ext2/Makefile
212 obj-$(CONFIG_EXT2_FS) += ext2.o 212 obj-$(CONFIG_EXT2_FS) += ext2.o
213 ext2-y := balloc.o bitmap.o 213 ext2-y := balloc.o bitmap.o
214 ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o 214 ext2-$(CONFIG_EXT2_FS_XATTR) += xattr.o
215 215
216 In this example, xattr.o is only part of the composite object 216 In this example, xattr.o is only part of the composite object
217 ext2.o if $(CONFIG_EXT2_FS_XATTR) evaluates to 'y'. 217 ext2.o if $(CONFIG_EXT2_FS_XATTR) evaluates to 'y'.
218 218
219 Note: Of course, when you are building objects into the kernel, 219 Note: Of course, when you are building objects into the kernel,
220 the syntax above will also work. So, if you have CONFIG_EXT2_FS=y, 220 the syntax above will also work. So, if you have CONFIG_EXT2_FS=y,
221 kbuild will build an ext2.o file for you out of the individual 221 kbuild will build an ext2.o file for you out of the individual
222 parts and then link this into built-in.o, as you would expect. 222 parts and then link this into built-in.o, as you would expect.
223 223
224 --- 3.4 Objects which export symbols 224 --- 3.4 Objects which export symbols
225 225
226 No special notation is required in the makefiles for 226 No special notation is required in the makefiles for
227 modules exporting symbols. 227 modules exporting symbols.
228 228
229 --- 3.5 Library file goals - lib-y 229 --- 3.5 Library file goals - lib-y
230 230
231 Objects listed with obj-* are used for modules, or 231 Objects listed with obj-* are used for modules, or
232 combined in a built-in.o for that specific directory. 232 combined in a built-in.o for that specific directory.
233 There is also the possibility to list objects that will 233 There is also the possibility to list objects that will
234 be included in a library, lib.a. 234 be included in a library, lib.a.
235 All objects listed with lib-y are combined in a single 235 All objects listed with lib-y are combined in a single
236 library for that directory. 236 library for that directory.
237 Objects that are listed in obj-y and additionally listed in 237 Objects that are listed in obj-y and additionally listed in
238 lib-y will not be included in the library, since they will 238 lib-y will not be included in the library, since they will
239 be accessible anyway. 239 be accessible anyway.
240 For consistency, objects listed in lib-m will be included in lib.a. 240 For consistency, objects listed in lib-m will be included in lib.a.
241 241
242 Note that the same kbuild makefile may list files to be built-in 242 Note that the same kbuild makefile may list files to be built-in
243 and to be part of a library. Therefore the same directory 243 and to be part of a library. Therefore the same directory
244 may contain both a built-in.o and a lib.a file. 244 may contain both a built-in.o and a lib.a file.
245 245
246 Example: 246 Example:
247 #arch/i386/lib/Makefile 247 #arch/i386/lib/Makefile
248 lib-y := checksum.o delay.o 248 lib-y := checksum.o delay.o
249 249
250 This will create a library lib.a based on checksum.o and delay.o. 250 This will create a library lib.a based on checksum.o and delay.o.
251 For kbuild to actually recognize that there is a lib.a being built, 251 For kbuild to actually recognize that there is a lib.a being built,
252 the directory shall be listed in libs-y. 252 the directory shall be listed in libs-y.
253 See also "6.3 List directories to visit when descending". 253 See also "6.3 List directories to visit when descending".
254 254
255 Use of lib-y is normally restricted to lib/ and arch/*/lib. 255 Use of lib-y is normally restricted to lib/ and arch/*/lib.
256 256
257 --- 3.6 Descending down in directories 257 --- 3.6 Descending down in directories
258 258
259 A Makefile is only responsible for building objects in its own 259 A Makefile is only responsible for building objects in its own
260 directory. Files in subdirectories should be taken care of by 260 directory. Files in subdirectories should be taken care of by
261 Makefiles in these subdirs. The build system will automatically 261 Makefiles in these subdirs. The build system will automatically
262 invoke make recursively in subdirectories, provided you let it know of 262 invoke make recursively in subdirectories, provided you let it know of
263 them. 263 them.
264 264
265 To do so, obj-y and obj-m are used. 265 To do so, obj-y and obj-m are used.
266 ext2 lives in a separate directory, and the Makefile present in fs/ 266 ext2 lives in a separate directory, and the Makefile present in fs/
267 tells kbuild to descend down using the following assignment. 267 tells kbuild to descend down using the following assignment.
268 268
269 Example: 269 Example:
270 #fs/Makefile 270 #fs/Makefile
271 obj-$(CONFIG_EXT2_FS) += ext2/ 271 obj-$(CONFIG_EXT2_FS) += ext2/
272 272
273 If CONFIG_EXT2_FS is set to either 'y' (built-in) or 'm' (modular) 273 If CONFIG_EXT2_FS is set to either 'y' (built-in) or 'm' (modular)
274 the corresponding obj- variable will be set, and kbuild will descend 274 the corresponding obj- variable will be set, and kbuild will descend
275 down in the ext2 directory. 275 down in the ext2 directory.
276 Kbuild only uses this information to decide that it needs to visit 276 Kbuild only uses this information to decide that it needs to visit
277 the directory, it is the Makefile in the subdirectory that 277 the directory, it is the Makefile in the subdirectory that
278 specifies what is modules and what is built-in. 278 specifies what is modules and what is built-in.
279 279
280 It is good practice to use a CONFIG_ variable when assigning directory 280 It is good practice to use a CONFIG_ variable when assigning directory
281 names. This allows kbuild to totally skip the directory if the 281 names. This allows kbuild to totally skip the directory if the
282 corresponding CONFIG_ option is neither 'y' nor 'm'. 282 corresponding CONFIG_ option is neither 'y' nor 'm'.
283 283
284 --- 3.7 Compilation flags 284 --- 3.7 Compilation flags
285 285
286 ccflags-y, asflags-y and ldflags-y 286 ccflags-y, asflags-y and ldflags-y
287 The three flags listed above applies only to the kbuild makefile 287 The three flags listed above applies only to the kbuild makefile
288 where they are assigned. They are used for all the normal 288 where they are assigned. They are used for all the normal
289 cc, as and ld invocation happenign during a recursive build. 289 cc, as and ld invocation happenign during a recursive build.
290 Note: Flags with the same behaviour were previously named: 290 Note: Flags with the same behaviour were previously named:
291 EXTRA_CFLAGS, EXTRA_AFLAGS and EXTRA_LDFLAGS. 291 EXTRA_CFLAGS, EXTRA_AFLAGS and EXTRA_LDFLAGS.
292 They are yet supported but their use are deprecated. 292 They are yet supported but their use are deprecated.
293 293
294 ccflags-y specifies options for compiling C files with $(CC). 294 ccflags-y specifies options for compiling C files with $(CC).
295 295
296 Example: 296 Example:
297 # drivers/sound/emu10k1/Makefile 297 # drivers/sound/emu10k1/Makefile
298 ccflags-y += -I$(obj) 298 ccflags-y += -I$(obj)
299 ccflags-$(DEBUG) += -DEMU10K1_DEBUG 299 ccflags-$(DEBUG) += -DEMU10K1_DEBUG
300 300
301 301
302 This variable is necessary because the top Makefile owns the 302 This variable is necessary because the top Makefile owns the
303 variable $(KBUILD_CFLAGS) and uses it for compilation flags for the 303 variable $(KBUILD_CFLAGS) and uses it for compilation flags for the
304 entire tree. 304 entire tree.
305 305
306 asflags-y is a similar string for per-directory options 306 asflags-y is a similar string for per-directory options
307 when compiling assembly language source. 307 when compiling assembly language source.
308 308
309 Example: 309 Example:
310 #arch/x86_64/kernel/Makefile 310 #arch/x86_64/kernel/Makefile
311 asflags-y := -traditional 311 asflags-y := -traditional
312 312
313 313
314 ldflags-y is a string for per-directory options to $(LD). 314 ldflags-y is a string for per-directory options to $(LD).
315 315
316 Example: 316 Example:
317 #arch/m68k/fpsp040/Makefile 317 #arch/m68k/fpsp040/Makefile
318 ldflags-y := -x 318 ldflags-y := -x
319 319
320 subdir-ccflags-y, subdir-asflags-y 320 subdir-ccflags-y, subdir-asflags-y
321 The two flags listed above are similar to ccflags-y and as-falgs-y. 321 The two flags listed above are similar to ccflags-y and as-falgs-y.
322 The difference is that the subdir- variants has effect for the kbuild 322 The difference is that the subdir- variants has effect for the kbuild
323 file where they are present and all subdirectories. 323 file where they are present and all subdirectories.
324 Options specified using subdir-* are added to the commandline before 324 Options specified using subdir-* are added to the commandline before
325 the options specified using the non-subdir variants. 325 the options specified using the non-subdir variants.
326 326
327 Example: 327 Example:
328 subdir-ccflags-y := -Werror 328 subdir-ccflags-y := -Werror
329 329
330 CFLAGS_$@, AFLAGS_$@ 330 CFLAGS_$@, AFLAGS_$@
331 331
332 CFLAGS_$@ and AFLAGS_$@ only apply to commands in current 332 CFLAGS_$@ and AFLAGS_$@ only apply to commands in current
333 kbuild makefile. 333 kbuild makefile.
334 334
335 $(CFLAGS_$@) specifies per-file options for $(CC). The $@ 335 $(CFLAGS_$@) specifies per-file options for $(CC). The $@
336 part has a literal value which specifies the file that it is for. 336 part has a literal value which specifies the file that it is for.
337 337
338 Example: 338 Example:
339 # drivers/scsi/Makefile 339 # drivers/scsi/Makefile
340 CFLAGS_aha152x.o = -DAHA152X_STAT -DAUTOCONF 340 CFLAGS_aha152x.o = -DAHA152X_STAT -DAUTOCONF
341 CFLAGS_gdth.o = # -DDEBUG_GDTH=2 -D__SERIAL__ -D__COM2__ \ 341 CFLAGS_gdth.o = # -DDEBUG_GDTH=2 -D__SERIAL__ -D__COM2__ \
342 -DGDTH_STATISTICS 342 -DGDTH_STATISTICS
343 CFLAGS_seagate.o = -DARBITRATE -DPARITY -DSEAGATE_USE_ASM 343 CFLAGS_seagate.o = -DARBITRATE -DPARITY -DSEAGATE_USE_ASM
344 344
345 These three lines specify compilation flags for aha152x.o, 345 These three lines specify compilation flags for aha152x.o,
346 gdth.o, and seagate.o 346 gdth.o, and seagate.o
347 347
348 $(AFLAGS_$@) is a similar feature for source files in assembly 348 $(AFLAGS_$@) is a similar feature for source files in assembly
349 languages. 349 languages.
350 350
351 Example: 351 Example:
352 # arch/arm/kernel/Makefile 352 # arch/arm/kernel/Makefile
353 AFLAGS_head-armv.o := -DTEXTADDR=$(TEXTADDR) -traditional 353 AFLAGS_head-armv.o := -DTEXTADDR=$(TEXTADDR) -traditional
354 AFLAGS_head-armo.o := -DTEXTADDR=$(TEXTADDR) -traditional 354 AFLAGS_head-armo.o := -DTEXTADDR=$(TEXTADDR) -traditional
355 355
356 --- 3.9 Dependency tracking 356 --- 3.9 Dependency tracking
357 357
358 Kbuild tracks dependencies on the following: 358 Kbuild tracks dependencies on the following:
359 1) All prerequisite files (both *.c and *.h) 359 1) All prerequisite files (both *.c and *.h)
360 2) CONFIG_ options used in all prerequisite files 360 2) CONFIG_ options used in all prerequisite files
361 3) Command-line used to compile target 361 3) Command-line used to compile target
362 362
363 Thus, if you change an option to $(CC) all affected files will 363 Thus, if you change an option to $(CC) all affected files will
364 be re-compiled. 364 be re-compiled.
365 365
366 --- 3.10 Special Rules 366 --- 3.10 Special Rules
367 367
368 Special rules are used when the kbuild infrastructure does 368 Special rules are used when the kbuild infrastructure does
369 not provide the required support. A typical example is 369 not provide the required support. A typical example is
370 header files generated during the build process. 370 header files generated during the build process.
371 Another example are the architecture-specific Makefiles which 371 Another example are the architecture-specific Makefiles which
372 need special rules to prepare boot images etc. 372 need special rules to prepare boot images etc.
373 373
374 Special rules are written as normal Make rules. 374 Special rules are written as normal Make rules.
375 Kbuild is not executing in the directory where the Makefile is 375 Kbuild is not executing in the directory where the Makefile is
376 located, so all special rules shall provide a relative 376 located, so all special rules shall provide a relative
377 path to prerequisite files and target files. 377 path to prerequisite files and target files.
378 378
379 Two variables are used when defining special rules: 379 Two variables are used when defining special rules:
380 380
381 $(src) 381 $(src)
382 $(src) is a relative path which points to the directory 382 $(src) is a relative path which points to the directory
383 where the Makefile is located. Always use $(src) when 383 where the Makefile is located. Always use $(src) when
384 referring to files located in the src tree. 384 referring to files located in the src tree.
385 385
386 $(obj) 386 $(obj)
387 $(obj) is a relative path which points to the directory 387 $(obj) is a relative path which points to the directory
388 where the target is saved. Always use $(obj) when 388 where the target is saved. Always use $(obj) when
389 referring to generated files. 389 referring to generated files.
390 390
391 Example: 391 Example:
392 #drivers/scsi/Makefile 392 #drivers/scsi/Makefile
393 $(obj)/53c8xx_d.h: $(src)/53c7,8xx.scr $(src)/script_asm.pl 393 $(obj)/53c8xx_d.h: $(src)/53c7,8xx.scr $(src)/script_asm.pl
394 $(CPP) -DCHIP=810 - < $< | ... $(src)/script_asm.pl 394 $(CPP) -DCHIP=810 - < $< | ... $(src)/script_asm.pl
395 395
396 This is a special rule, following the normal syntax 396 This is a special rule, following the normal syntax
397 required by make. 397 required by make.
398 The target file depends on two prerequisite files. References 398 The target file depends on two prerequisite files. References
399 to the target file are prefixed with $(obj), references 399 to the target file are prefixed with $(obj), references
400 to prerequisites are referenced with $(src) (because they are not 400 to prerequisites are referenced with $(src) (because they are not
401 generated files). 401 generated files).
402 402
403 $(kecho) 403 $(kecho)
404 echoing information to user in a rule is often a good practice 404 echoing information to user in a rule is often a good practice
405 but when execution "make -s" one does not expect to see any output 405 but when execution "make -s" one does not expect to see any output
406 except for warnings/errors. 406 except for warnings/errors.
407 To support this kbuild define $(kecho) which will echo out the 407 To support this kbuild define $(kecho) which will echo out the
408 text following $(kecho) to stdout except if "make -s" is used. 408 text following $(kecho) to stdout except if "make -s" is used.
409 409
410 Example: 410 Example:
411 #arch/blackfin/boot/Makefile 411 #arch/blackfin/boot/Makefile
412 $(obj)/vmImage: $(obj)/vmlinux.gz 412 $(obj)/vmImage: $(obj)/vmlinux.gz
413 $(call if_changed,uimage) 413 $(call if_changed,uimage)
414 @$(kecho) 'Kernel: $@ is ready' 414 @$(kecho) 'Kernel: $@ is ready'
415 415
416 416
417 --- 3.11 $(CC) support functions 417 --- 3.11 $(CC) support functions
418 418
419 The kernel may be built with several different versions of 419 The kernel may be built with several different versions of
420 $(CC), each supporting a unique set of features and options. 420 $(CC), each supporting a unique set of features and options.
421 kbuild provide basic support to check for valid options for $(CC). 421 kbuild provide basic support to check for valid options for $(CC).
422 $(CC) is usually the gcc compiler, but other alternatives are 422 $(CC) is usually the gcc compiler, but other alternatives are
423 available. 423 available.
424 424
425 as-option 425 as-option
426 as-option is used to check if $(CC) -- when used to compile 426 as-option is used to check if $(CC) -- when used to compile
427 assembler (*.S) files -- supports the given option. An optional 427 assembler (*.S) files -- supports the given option. An optional
428 second option may be specified if the first option is not supported. 428 second option may be specified if the first option is not supported.
429 429
430 Example: 430 Example:
431 #arch/sh/Makefile 431 #arch/sh/Makefile
432 cflags-y += $(call as-option,-Wa$(comma)-isa=$(isa-y),) 432 cflags-y += $(call as-option,-Wa$(comma)-isa=$(isa-y),)
433 433
434 In the above example, cflags-y will be assigned the option 434 In the above example, cflags-y will be assigned the option
435 -Wa$(comma)-isa=$(isa-y) if it is supported by $(CC). 435 -Wa$(comma)-isa=$(isa-y) if it is supported by $(CC).
436 The second argument is optional, and if supplied will be used 436 The second argument is optional, and if supplied will be used
437 if first argument is not supported. 437 if first argument is not supported.
438 438
439 cc-ldoption 439 cc-ldoption
440 cc-ldoption is used to check if $(CC) when used to link object files 440 cc-ldoption is used to check if $(CC) when used to link object files
441 supports the given option. An optional second option may be 441 supports the given option. An optional second option may be
442 specified if first option are not supported. 442 specified if first option are not supported.
443 443
444 Example: 444 Example:
445 #arch/i386/kernel/Makefile 445 #arch/i386/kernel/Makefile
446 vsyscall-flags += $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) 446 vsyscall-flags += $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
447 447
448 In the above example, vsyscall-flags will be assigned the option 448 In the above example, vsyscall-flags will be assigned the option
449 -Wl$(comma)--hash-style=sysv if it is supported by $(CC). 449 -Wl$(comma)--hash-style=sysv if it is supported by $(CC).
450 The second argument is optional, and if supplied will be used 450 The second argument is optional, and if supplied will be used
451 if first argument is not supported. 451 if first argument is not supported.
452 452
453 as-instr 453 as-instr
454 as-instr checks if the assembler reports a specific instruction 454 as-instr checks if the assembler reports a specific instruction
455 and then outputs either option1 or option2 455 and then outputs either option1 or option2
456 C escapes are supported in the test instruction 456 C escapes are supported in the test instruction
457 Note: as-instr-option uses KBUILD_AFLAGS for $(AS) options 457 Note: as-instr-option uses KBUILD_AFLAGS for $(AS) options
458 458
459 cc-option 459 cc-option
460 cc-option is used to check if $(CC) supports a given option, and not 460 cc-option is used to check if $(CC) supports a given option, and not
461 supported to use an optional second option. 461 supported to use an optional second option.
462 462
463 Example: 463 Example:
464 #arch/i386/Makefile 464 #arch/i386/Makefile
465 cflags-y += $(call cc-option,-march=pentium-mmx,-march=i586) 465 cflags-y += $(call cc-option,-march=pentium-mmx,-march=i586)
466 466
467 In the above example, cflags-y will be assigned the option 467 In the above example, cflags-y will be assigned the option
468 -march=pentium-mmx if supported by $(CC), otherwise -march=i586. 468 -march=pentium-mmx if supported by $(CC), otherwise -march=i586.
469 The second argument to cc-option is optional, and if omitted, 469 The second argument to cc-option is optional, and if omitted,
470 cflags-y will be assigned no value if first option is not supported. 470 cflags-y will be assigned no value if first option is not supported.
471 Note: cc-option uses KBUILD_CFLAGS for $(CC) options 471 Note: cc-option uses KBUILD_CFLAGS for $(CC) options
472 472
473 cc-option-yn 473 cc-option-yn
474 cc-option-yn is used to check if gcc supports a given option 474 cc-option-yn is used to check if gcc supports a given option
475 and return 'y' if supported, otherwise 'n'. 475 and return 'y' if supported, otherwise 'n'.
476 476
477 Example: 477 Example:
478 #arch/ppc/Makefile 478 #arch/ppc/Makefile
479 biarch := $(call cc-option-yn, -m32) 479 biarch := $(call cc-option-yn, -m32)
480 aflags-$(biarch) += -a32 480 aflags-$(biarch) += -a32
481 cflags-$(biarch) += -m32 481 cflags-$(biarch) += -m32
482 482
483 In the above example, $(biarch) is set to y if $(CC) supports the -m32 483 In the above example, $(biarch) is set to y if $(CC) supports the -m32
484 option. When $(biarch) equals 'y', the expanded variables $(aflags-y) 484 option. When $(biarch) equals 'y', the expanded variables $(aflags-y)
485 and $(cflags-y) will be assigned the values -a32 and -m32, 485 and $(cflags-y) will be assigned the values -a32 and -m32,
486 respectively. 486 respectively.
487 Note: cc-option-yn uses KBUILD_CFLAGS for $(CC) options 487 Note: cc-option-yn uses KBUILD_CFLAGS for $(CC) options
488 488
489 cc-option-align 489 cc-option-align
490 gcc versions >= 3.0 changed the type of options used to specify 490 gcc versions >= 3.0 changed the type of options used to specify
491 alignment of functions, loops etc. $(cc-option-align), when used 491 alignment of functions, loops etc. $(cc-option-align), when used
492 as prefix to the align options, will select the right prefix: 492 as prefix to the align options, will select the right prefix:
493 gcc < 3.00 493 gcc < 3.00
494 cc-option-align = -malign 494 cc-option-align = -malign
495 gcc >= 3.00 495 gcc >= 3.00
496 cc-option-align = -falign 496 cc-option-align = -falign
497 497
498 Example: 498 Example:
499 KBUILD_CFLAGS += $(cc-option-align)-functions=4 499 KBUILD_CFLAGS += $(cc-option-align)-functions=4
500 500
501 In the above example, the option -falign-functions=4 is used for 501 In the above example, the option -falign-functions=4 is used for
502 gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used. 502 gcc >= 3.00. For gcc < 3.00, -malign-functions=4 is used.
503 Note: cc-option-align uses KBUILD_CFLAGS for $(CC) options 503 Note: cc-option-align uses KBUILD_CFLAGS for $(CC) options
504 504
505 cc-version 505 cc-version
506 cc-version returns a numerical version of the $(CC) compiler version. 506 cc-version returns a numerical version of the $(CC) compiler version.
507 The format is <major><minor> where both are two digits. So for example 507 The format is <major><minor> where both are two digits. So for example
508 gcc 3.41 would return 0341. 508 gcc 3.41 would return 0341.
509 cc-version is useful when a specific $(CC) version is faulty in one 509 cc-version is useful when a specific $(CC) version is faulty in one
510 area, for example -mregparm=3 was broken in some gcc versions 510 area, for example -mregparm=3 was broken in some gcc versions
511 even though the option was accepted by gcc. 511 even though the option was accepted by gcc.
512 512
513 Example: 513 Example:
514 #arch/i386/Makefile 514 #arch/i386/Makefile
515 cflags-y += $(shell \ 515 cflags-y += $(shell \
516 if [ $(call cc-version) -ge 0300 ] ; then \ 516 if [ $(call cc-version) -ge 0300 ] ; then \
517 echo "-mregparm=3"; fi ;) 517 echo "-mregparm=3"; fi ;)
518 518
519 In the above example, -mregparm=3 is only used for gcc version greater 519 In the above example, -mregparm=3 is only used for gcc version greater
520 than or equal to gcc 3.0. 520 than or equal to gcc 3.0.
521 521
522 cc-ifversion 522 cc-ifversion
523 cc-ifversion tests the version of $(CC) and equals last argument if 523 cc-ifversion tests the version of $(CC) and equals last argument if
524 version expression is true. 524 version expression is true.
525 525
526 Example: 526 Example:
527 #fs/reiserfs/Makefile 527 #fs/reiserfs/Makefile
528 ccflags-y := $(call cc-ifversion, -lt, 0402, -O1) 528 ccflags-y := $(call cc-ifversion, -lt, 0402, -O1)
529 529
530 In this example, ccflags-y will be assigned the value -O1 if the 530 In this example, ccflags-y will be assigned the value -O1 if the
531 $(CC) version is less than 4.2. 531 $(CC) version is less than 4.2.
532 cc-ifversion takes all the shell operators: 532 cc-ifversion takes all the shell operators:
533 -eq, -ne, -lt, -le, -gt, and -ge 533 -eq, -ne, -lt, -le, -gt, and -ge
534 The third parameter may be a text as in this example, but it may also 534 The third parameter may be a text as in this example, but it may also
535 be an expanded variable or a macro. 535 be an expanded variable or a macro.
536 536
537 cc-fullversion 537 cc-fullversion
538 cc-fullversion is useful when the exact version of gcc is needed. 538 cc-fullversion is useful when the exact version of gcc is needed.
539 One typical use-case is when a specific GCC version is broken. 539 One typical use-case is when a specific GCC version is broken.
540 cc-fullversion points out a more specific version than cc-version does. 540 cc-fullversion points out a more specific version than cc-version does.
541 541
542 Example: 542 Example:
543 #arch/powerpc/Makefile 543 #arch/powerpc/Makefile
544 $(Q)if test "$(call cc-fullversion)" = "040200" ; then \ 544 $(Q)if test "$(call cc-fullversion)" = "040200" ; then \
545 echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \ 545 echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \
546 false ; \ 546 false ; \
547 fi 547 fi
548 548
549 In this example for a specific GCC version the build will error out explaining 549 In this example for a specific GCC version the build will error out explaining
550 to the user why it stops. 550 to the user why it stops.
551 551
552 cc-cross-prefix 552 cc-cross-prefix
553 cc-cross-prefix is used to check if there exists a $(CC) in path with 553 cc-cross-prefix is used to check if there exists a $(CC) in path with
554 one of the listed prefixes. The first prefix where there exist a 554 one of the listed prefixes. The first prefix where there exist a
555 prefix$(CC) in the PATH is returned - and if no prefix$(CC) is found 555 prefix$(CC) in the PATH is returned - and if no prefix$(CC) is found
556 then nothing is returned. 556 then nothing is returned.
557 Additional prefixes are separated by a single space in the 557 Additional prefixes are separated by a single space in the
558 call of cc-cross-prefix. 558 call of cc-cross-prefix.
559 This functionality is useful for architecture Makefiles that try 559 This functionality is useful for architecture Makefiles that try
560 to set CROSS_COMPILE to well-known values but may have several 560 to set CROSS_COMPILE to well-known values but may have several
561 values to select between. 561 values to select between.
562 It is recommended only to try to set CROSS_COMPILE if it is a cross 562 It is recommended only to try to set CROSS_COMPILE if it is a cross
563 build (host arch is different from target arch). And if CROSS_COMPILE 563 build (host arch is different from target arch). And if CROSS_COMPILE
564 is already set then leave it with the old value. 564 is already set then leave it with the old value.
565 565
566 Example: 566 Example:
567 #arch/m68k/Makefile 567 #arch/m68k/Makefile
568 ifneq ($(SUBARCH),$(ARCH)) 568 ifneq ($(SUBARCH),$(ARCH))
569 ifeq ($(CROSS_COMPILE),) 569 ifeq ($(CROSS_COMPILE),)
570 CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu-) 570 CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu-)
571 endif 571 endif
572 endif 572 endif
573 573
574 --- 3.12 $(LD) support functions 574 --- 3.12 $(LD) support functions
575 575
576 ld-option 576 ld-option
577 ld-option is used to check if $(LD) supports the supplied option. 577 ld-option is used to check if $(LD) supports the supplied option.
578 ld-option takes two options as arguments. 578 ld-option takes two options as arguments.
579 The second argument is an optional option that can be used if the 579 The second argument is an optional option that can be used if the
580 first option is not supported by $(LD). 580 first option is not supported by $(LD).
581 581
582 Example: 582 Example:
583 #Makefile 583 #Makefile
584 LDFLAGS_vmlinux += $(call really-ld-option, -X) 584 LDFLAGS_vmlinux += $(call really-ld-option, -X)
585 585
586 586
587 === 4 Host Program support 587 === 4 Host Program support
588 588
589 Kbuild supports building executables on the host for use during the 589 Kbuild supports building executables on the host for use during the
590 compilation stage. 590 compilation stage.
591 Two steps are required in order to use a host executable. 591 Two steps are required in order to use a host executable.
592 592
593 The first step is to tell kbuild that a host program exists. This is 593 The first step is to tell kbuild that a host program exists. This is
594 done utilising the variable hostprogs-y. 594 done utilising the variable hostprogs-y.
595 595
596 The second step is to add an explicit dependency to the executable. 596 The second step is to add an explicit dependency to the executable.
597 This can be done in two ways. Either add the dependency in a rule, 597 This can be done in two ways. Either add the dependency in a rule,
598 or utilise the variable $(always). 598 or utilise the variable $(always).
599 Both possibilities are described in the following. 599 Both possibilities are described in the following.
600 600
601 --- 4.1 Simple Host Program 601 --- 4.1 Simple Host Program
602 602
603 In some cases there is a need to compile and run a program on the 603 In some cases there is a need to compile and run a program on the
604 computer where the build is running. 604 computer where the build is running.
605 The following line tells kbuild that the program bin2hex shall be 605 The following line tells kbuild that the program bin2hex shall be
606 built on the build host. 606 built on the build host.
607 607
608 Example: 608 Example:
609 hostprogs-y := bin2hex 609 hostprogs-y := bin2hex
610 610
611 Kbuild assumes in the above example that bin2hex is made from a single 611 Kbuild assumes in the above example that bin2hex is made from a single
612 c-source file named bin2hex.c located in the same directory as 612 c-source file named bin2hex.c located in the same directory as
613 the Makefile. 613 the Makefile.
614 614
615 --- 4.2 Composite Host Programs 615 --- 4.2 Composite Host Programs
616 616
617 Host programs can be made up based on composite objects. 617 Host programs can be made up based on composite objects.
618 The syntax used to define composite objects for host programs is 618 The syntax used to define composite objects for host programs is
619 similar to the syntax used for kernel objects. 619 similar to the syntax used for kernel objects.
620 $(<executable>-objs) lists all objects used to link the final 620 $(<executable>-objs) lists all objects used to link the final
621 executable. 621 executable.
622 622
623 Example: 623 Example:
624 #scripts/lxdialog/Makefile 624 #scripts/lxdialog/Makefile
625 hostprogs-y := lxdialog 625 hostprogs-y := lxdialog
626 lxdialog-objs := checklist.o lxdialog.o 626 lxdialog-objs := checklist.o lxdialog.o
627 627
628 Objects with extension .o are compiled from the corresponding .c 628 Objects with extension .o are compiled from the corresponding .c
629 files. In the above example, checklist.c is compiled to checklist.o 629 files. In the above example, checklist.c is compiled to checklist.o
630 and lxdialog.c is compiled to lxdialog.o. 630 and lxdialog.c is compiled to lxdialog.o.
631 Finally, the two .o files are linked to the executable, lxdialog. 631 Finally, the two .o files are linked to the executable, lxdialog.
632 Note: The syntax <executable>-y is not permitted for host-programs. 632 Note: The syntax <executable>-y is not permitted for host-programs.
633 633
634 --- 4.3 Defining shared libraries 634 --- 4.3 Defining shared libraries
635 635
636 Objects with extension .so are considered shared libraries, and 636 Objects with extension .so are considered shared libraries, and
637 will be compiled as position independent objects. 637 will be compiled as position independent objects.
638 Kbuild provides support for shared libraries, but the usage 638 Kbuild provides support for shared libraries, but the usage
639 shall be restricted. 639 shall be restricted.
640 In the following example the libkconfig.so shared library is used 640 In the following example the libkconfig.so shared library is used
641 to link the executable conf. 641 to link the executable conf.
642 642
643 Example: 643 Example:
644 #scripts/kconfig/Makefile 644 #scripts/kconfig/Makefile
645 hostprogs-y := conf 645 hostprogs-y := conf
646 conf-objs := conf.o libkconfig.so 646 conf-objs := conf.o libkconfig.so
647 libkconfig-objs := expr.o type.o 647 libkconfig-objs := expr.o type.o
648 648
649 Shared libraries always require a corresponding -objs line, and 649 Shared libraries always require a corresponding -objs line, and
650 in the example above the shared library libkconfig is composed by 650 in the example above the shared library libkconfig is composed by
651 the two objects expr.o and type.o. 651 the two objects expr.o and type.o.
652 expr.o and type.o will be built as position independent code and 652 expr.o and type.o will be built as position independent code and
653 linked as a shared library libkconfig.so. C++ is not supported for 653 linked as a shared library libkconfig.so. C++ is not supported for
654 shared libraries. 654 shared libraries.
655 655
656 --- 4.4 Using C++ for host programs 656 --- 4.4 Using C++ for host programs
657 657
658 kbuild offers support for host programs written in C++. This was 658 kbuild offers support for host programs written in C++. This was
659 introduced solely to support kconfig, and is not recommended 659 introduced solely to support kconfig, and is not recommended
660 for general use. 660 for general use.
661 661
662 Example: 662 Example:
663 #scripts/kconfig/Makefile 663 #scripts/kconfig/Makefile
664 hostprogs-y := qconf 664 hostprogs-y := qconf
665 qconf-cxxobjs := qconf.o 665 qconf-cxxobjs := qconf.o
666 666
667 In the example above the executable is composed of the C++ file 667 In the example above the executable is composed of the C++ file
668 qconf.cc - identified by $(qconf-cxxobjs). 668 qconf.cc - identified by $(qconf-cxxobjs).
669 669
670 If qconf is composed by a mixture of .c and .cc files, then an 670 If qconf is composed by a mixture of .c and .cc files, then an
671 additional line can be used to identify this. 671 additional line can be used to identify this.
672 672
673 Example: 673 Example:
674 #scripts/kconfig/Makefile 674 #scripts/kconfig/Makefile
675 hostprogs-y := qconf 675 hostprogs-y := qconf
676 qconf-cxxobjs := qconf.o 676 qconf-cxxobjs := qconf.o
677 qconf-objs := check.o 677 qconf-objs := check.o
678 678
679 --- 4.5 Controlling compiler options for host programs 679 --- 4.5 Controlling compiler options for host programs
680 680
681 When compiling host programs, it is possible to set specific flags. 681 When compiling host programs, it is possible to set specific flags.
682 The programs will always be compiled utilising $(HOSTCC) passed 682 The programs will always be compiled utilising $(HOSTCC) passed
683 the options specified in $(HOSTCFLAGS). 683 the options specified in $(HOSTCFLAGS).
684 To set flags that will take effect for all host programs created 684 To set flags that will take effect for all host programs created
685 in that Makefile, use the variable HOST_EXTRACFLAGS. 685 in that Makefile, use the variable HOST_EXTRACFLAGS.
686 686
687 Example: 687 Example:
688 #scripts/lxdialog/Makefile 688 #scripts/lxdialog/Makefile
689 HOST_EXTRACFLAGS += -I/usr/include/ncurses 689 HOST_EXTRACFLAGS += -I/usr/include/ncurses
690 690
691 To set specific flags for a single file the following construction 691 To set specific flags for a single file the following construction
692 is used: 692 is used:
693 693
694 Example: 694 Example:
695 #arch/ppc64/boot/Makefile 695 #arch/ppc64/boot/Makefile
696 HOSTCFLAGS_piggyback.o := -DKERNELBASE=$(KERNELBASE) 696 HOSTCFLAGS_piggyback.o := -DKERNELBASE=$(KERNELBASE)
697 697
698 It is also possible to specify additional options to the linker. 698 It is also possible to specify additional options to the linker.
699 699
700 Example: 700 Example:
701 #scripts/kconfig/Makefile 701 #scripts/kconfig/Makefile
702 HOSTLOADLIBES_qconf := -L$(QTDIR)/lib 702 HOSTLOADLIBES_qconf := -L$(QTDIR)/lib
703 703
704 When linking qconf, it will be passed the extra option 704 When linking qconf, it will be passed the extra option
705 "-L$(QTDIR)/lib". 705 "-L$(QTDIR)/lib".
706 706
707 --- 4.6 When host programs are actually built 707 --- 4.6 When host programs are actually built
708 708
709 Kbuild will only build host-programs when they are referenced 709 Kbuild will only build host-programs when they are referenced
710 as a prerequisite. 710 as a prerequisite.
711 This is possible in two ways: 711 This is possible in two ways:
712 712
713 (1) List the prerequisite explicitly in a special rule. 713 (1) List the prerequisite explicitly in a special rule.
714 714
715 Example: 715 Example:
716 #drivers/pci/Makefile 716 #drivers/pci/Makefile
717 hostprogs-y := gen-devlist 717 hostprogs-y := gen-devlist
718 $(obj)/devlist.h: $(src)/pci.ids $(obj)/gen-devlist 718 $(obj)/devlist.h: $(src)/pci.ids $(obj)/gen-devlist
719 ( cd $(obj); ./gen-devlist ) < $< 719 ( cd $(obj); ./gen-devlist ) < $<
720 720
721 The target $(obj)/devlist.h will not be built before 721 The target $(obj)/devlist.h will not be built before
722 $(obj)/gen-devlist is updated. Note that references to 722 $(obj)/gen-devlist is updated. Note that references to
723 the host programs in special rules must be prefixed with $(obj). 723 the host programs in special rules must be prefixed with $(obj).
724 724
725 (2) Use $(always) 725 (2) Use $(always)
726 When there is no suitable special rule, and the host program 726 When there is no suitable special rule, and the host program
727 shall be built when a makefile is entered, the $(always) 727 shall be built when a makefile is entered, the $(always)
728 variable shall be used. 728 variable shall be used.
729 729
730 Example: 730 Example:
731 #scripts/lxdialog/Makefile 731 #scripts/lxdialog/Makefile
732 hostprogs-y := lxdialog 732 hostprogs-y := lxdialog
733 always := $(hostprogs-y) 733 always := $(hostprogs-y)
734 734
735 This will tell kbuild to build lxdialog even if not referenced in 735 This will tell kbuild to build lxdialog even if not referenced in
736 any rule. 736 any rule.
737 737
738 --- 4.7 Using hostprogs-$(CONFIG_FOO) 738 --- 4.7 Using hostprogs-$(CONFIG_FOO)
739 739
740 A typical pattern in a Kbuild file looks like this: 740 A typical pattern in a Kbuild file looks like this:
741 741
742 Example: 742 Example:
743 #scripts/Makefile 743 #scripts/Makefile
744 hostprogs-$(CONFIG_KALLSYMS) += kallsyms 744 hostprogs-$(CONFIG_KALLSYMS) += kallsyms
745 745
746 Kbuild knows about both 'y' for built-in and 'm' for module. 746 Kbuild knows about both 'y' for built-in and 'm' for module.
747 So if a config symbol evaluate to 'm', kbuild will still build 747 So if a config symbol evaluate to 'm', kbuild will still build
748 the binary. In other words, Kbuild handles hostprogs-m exactly 748 the binary. In other words, Kbuild handles hostprogs-m exactly
749 like hostprogs-y. But only hostprogs-y is recommended to be used 749 like hostprogs-y. But only hostprogs-y is recommended to be used
750 when no CONFIG symbols are involved. 750 when no CONFIG symbols are involved.
751 751
752 === 5 Kbuild clean infrastructure 752 === 5 Kbuild clean infrastructure
753 753
754 "make clean" deletes most generated files in the obj tree where the kernel 754 "make clean" deletes most generated files in the obj tree where the kernel
755 is compiled. This includes generated files such as host programs. 755 is compiled. This includes generated files such as host programs.
756 Kbuild knows targets listed in $(hostprogs-y), $(hostprogs-m), $(always), 756 Kbuild knows targets listed in $(hostprogs-y), $(hostprogs-m), $(always),
757 $(extra-y) and $(targets). They are all deleted during "make clean". 757 $(extra-y) and $(targets). They are all deleted during "make clean".
758 Files matching the patterns "*.[oas]", "*.ko", plus some additional files 758 Files matching the patterns "*.[oas]", "*.ko", plus some additional files
759 generated by kbuild are deleted all over the kernel src tree when 759 generated by kbuild are deleted all over the kernel src tree when
760 "make clean" is executed. 760 "make clean" is executed.
761 761
762 Additional files can be specified in kbuild makefiles by use of $(clean-files). 762 Additional files can be specified in kbuild makefiles by use of $(clean-files).
763 763
764 Example: 764 Example:
765 #drivers/pci/Makefile 765 #drivers/pci/Makefile
766 clean-files := devlist.h classlist.h 766 clean-files := devlist.h classlist.h
767 767
768 When executing "make clean", the two files "devlist.h classlist.h" will 768 When executing "make clean", the two files "devlist.h classlist.h" will
769 be deleted. Kbuild will assume files to be in same relative directory as the 769 be deleted. Kbuild will assume files to be in same relative directory as the
770 Makefile except if an absolute path is specified (path starting with '/'). 770 Makefile except if an absolute path is specified (path starting with '/').
771 771
772 To delete a directory hierarchy use: 772 To delete a directory hierarchy use:
773 773
774 Example: 774 Example:
775 #scripts/package/Makefile 775 #scripts/package/Makefile
776 clean-dirs := $(objtree)/debian/ 776 clean-dirs := $(objtree)/debian/
777 777
778 This will delete the directory debian, including all subdirectories. 778 This will delete the directory debian, including all subdirectories.
779 Kbuild will assume the directories to be in the same relative path as the 779 Kbuild will assume the directories to be in the same relative path as the
780 Makefile if no absolute path is specified (path does not start with '/'). 780 Makefile if no absolute path is specified (path does not start with '/').
781 781
782 To exclude certain files from make clean, use the $(no-clean-files) variable.
783 This is only a special case used in the top level Kbuild file:
784
785 Example:
786 #Kbuild
787 no-clean-files := $(bounds-file) $(offsets-file)
788
782 Usually kbuild descends down in subdirectories due to "obj-* := dir/", 789 Usually kbuild descends down in subdirectories due to "obj-* := dir/",
783 but in the architecture makefiles where the kbuild infrastructure 790 but in the architecture makefiles where the kbuild infrastructure
784 is not sufficient this sometimes needs to be explicit. 791 is not sufficient this sometimes needs to be explicit.
785 792
786 Example: 793 Example:
787 #arch/i386/boot/Makefile 794 #arch/i386/boot/Makefile
788 subdir- := compressed/ 795 subdir- := compressed/
789 796
790 The above assignment instructs kbuild to descend down in the 797 The above assignment instructs kbuild to descend down in the
791 directory compressed/ when "make clean" is executed. 798 directory compressed/ when "make clean" is executed.
792 799
793 To support the clean infrastructure in the Makefiles that builds the 800 To support the clean infrastructure in the Makefiles that builds the
794 final bootimage there is an optional target named archclean: 801 final bootimage there is an optional target named archclean:
795 802
796 Example: 803 Example:
797 #arch/i386/Makefile 804 #arch/i386/Makefile
798 archclean: 805 archclean:
799 $(Q)$(MAKE) $(clean)=arch/i386/boot 806 $(Q)$(MAKE) $(clean)=arch/i386/boot
800 807
801 When "make clean" is executed, make will descend down in arch/i386/boot, 808 When "make clean" is executed, make will descend down in arch/i386/boot,
802 and clean as usual. The Makefile located in arch/i386/boot/ may use 809 and clean as usual. The Makefile located in arch/i386/boot/ may use
803 the subdir- trick to descend further down. 810 the subdir- trick to descend further down.
804 811
805 Note 1: arch/$(ARCH)/Makefile cannot use "subdir-", because that file is 812 Note 1: arch/$(ARCH)/Makefile cannot use "subdir-", because that file is
806 included in the top level makefile, and the kbuild infrastructure 813 included in the top level makefile, and the kbuild infrastructure
807 is not operational at that point. 814 is not operational at that point.
808 815
809 Note 2: All directories listed in core-y, libs-y, drivers-y and net-y will 816 Note 2: All directories listed in core-y, libs-y, drivers-y and net-y will
810 be visited during "make clean". 817 be visited during "make clean".
811 818
812 === 6 Architecture Makefiles 819 === 6 Architecture Makefiles
813 820
814 The top level Makefile sets up the environment and does the preparation, 821 The top level Makefile sets up the environment and does the preparation,
815 before starting to descend down in the individual directories. 822 before starting to descend down in the individual directories.
816 The top level makefile contains the generic part, whereas 823 The top level makefile contains the generic part, whereas
817 arch/$(ARCH)/Makefile contains what is required to set up kbuild 824 arch/$(ARCH)/Makefile contains what is required to set up kbuild
818 for said architecture. 825 for said architecture.
819 To do so, arch/$(ARCH)/Makefile sets up a number of variables and defines 826 To do so, arch/$(ARCH)/Makefile sets up a number of variables and defines
820 a few targets. 827 a few targets.
821 828
822 When kbuild executes, the following steps are followed (roughly): 829 When kbuild executes, the following steps are followed (roughly):
823 1) Configuration of the kernel => produce .config 830 1) Configuration of the kernel => produce .config
824 2) Store kernel version in include/linux/version.h 831 2) Store kernel version in include/linux/version.h
825 3) Symlink include/asm to include/asm-$(ARCH) 832 3) Symlink include/asm to include/asm-$(ARCH)
826 4) Updating all other prerequisites to the target prepare: 833 4) Updating all other prerequisites to the target prepare:
827 - Additional prerequisites are specified in arch/$(ARCH)/Makefile 834 - Additional prerequisites are specified in arch/$(ARCH)/Makefile
828 5) Recursively descend down in all directories listed in 835 5) Recursively descend down in all directories listed in
829 init-* core* drivers-* net-* libs-* and build all targets. 836 init-* core* drivers-* net-* libs-* and build all targets.
830 - The values of the above variables are expanded in arch/$(ARCH)/Makefile. 837 - The values of the above variables are expanded in arch/$(ARCH)/Makefile.
831 6) All object files are then linked and the resulting file vmlinux is 838 6) All object files are then linked and the resulting file vmlinux is
832 located at the root of the obj tree. 839 located at the root of the obj tree.
833 The very first objects linked are listed in head-y, assigned by 840 The very first objects linked are listed in head-y, assigned by
834 arch/$(ARCH)/Makefile. 841 arch/$(ARCH)/Makefile.
835 7) Finally, the architecture-specific part does any required post processing 842 7) Finally, the architecture-specific part does any required post processing
836 and builds the final bootimage. 843 and builds the final bootimage.
837 - This includes building boot records 844 - This includes building boot records
838 - Preparing initrd images and the like 845 - Preparing initrd images and the like
839 846
840 847
841 --- 6.1 Set variables to tweak the build to the architecture 848 --- 6.1 Set variables to tweak the build to the architecture
842 849
843 LDFLAGS Generic $(LD) options 850 LDFLAGS Generic $(LD) options
844 851
845 Flags used for all invocations of the linker. 852 Flags used for all invocations of the linker.
846 Often specifying the emulation is sufficient. 853 Often specifying the emulation is sufficient.
847 854
848 Example: 855 Example:
849 #arch/s390/Makefile 856 #arch/s390/Makefile
850 LDFLAGS := -m elf_s390 857 LDFLAGS := -m elf_s390
851 Note: ldflags-y can be used to further customise 858 Note: ldflags-y can be used to further customise
852 the flags used. See chapter 3.7. 859 the flags used. See chapter 3.7.
853 860
854 LDFLAGS_MODULE Options for $(LD) when linking modules 861 LDFLAGS_MODULE Options for $(LD) when linking modules
855 862
856 LDFLAGS_MODULE is used to set specific flags for $(LD) when 863 LDFLAGS_MODULE is used to set specific flags for $(LD) when
857 linking the .ko files used for modules. 864 linking the .ko files used for modules.
858 Default is "-r", for relocatable output. 865 Default is "-r", for relocatable output.
859 866
860 LDFLAGS_vmlinux Options for $(LD) when linking vmlinux 867 LDFLAGS_vmlinux Options for $(LD) when linking vmlinux
861 868
862 LDFLAGS_vmlinux is used to specify additional flags to pass to 869 LDFLAGS_vmlinux is used to specify additional flags to pass to
863 the linker when linking the final vmlinux image. 870 the linker when linking the final vmlinux image.
864 LDFLAGS_vmlinux uses the LDFLAGS_$@ support. 871 LDFLAGS_vmlinux uses the LDFLAGS_$@ support.
865 872
866 Example: 873 Example:
867 #arch/i386/Makefile 874 #arch/i386/Makefile
868 LDFLAGS_vmlinux := -e stext 875 LDFLAGS_vmlinux := -e stext
869 876
870 OBJCOPYFLAGS objcopy flags 877 OBJCOPYFLAGS objcopy flags
871 878
872 When $(call if_changed,objcopy) is used to translate a .o file, 879 When $(call if_changed,objcopy) is used to translate a .o file,
873 the flags specified in OBJCOPYFLAGS will be used. 880 the flags specified in OBJCOPYFLAGS will be used.
874 $(call if_changed,objcopy) is often used to generate raw binaries on 881 $(call if_changed,objcopy) is often used to generate raw binaries on
875 vmlinux. 882 vmlinux.
876 883
877 Example: 884 Example:
878 #arch/s390/Makefile 885 #arch/s390/Makefile
879 OBJCOPYFLAGS := -O binary 886 OBJCOPYFLAGS := -O binary
880 887
881 #arch/s390/boot/Makefile 888 #arch/s390/boot/Makefile
882 $(obj)/image: vmlinux FORCE 889 $(obj)/image: vmlinux FORCE
883 $(call if_changed,objcopy) 890 $(call if_changed,objcopy)
884 891
885 In this example, the binary $(obj)/image is a binary version of 892 In this example, the binary $(obj)/image is a binary version of
886 vmlinux. The usage of $(call if_changed,xxx) will be described later. 893 vmlinux. The usage of $(call if_changed,xxx) will be described later.
887 894
888 KBUILD_AFLAGS $(AS) assembler flags 895 KBUILD_AFLAGS $(AS) assembler flags
889 896
890 Default value - see top level Makefile 897 Default value - see top level Makefile
891 Append or modify as required per architecture. 898 Append or modify as required per architecture.
892 899
893 Example: 900 Example:
894 #arch/sparc64/Makefile 901 #arch/sparc64/Makefile
895 KBUILD_AFLAGS += -m64 -mcpu=ultrasparc 902 KBUILD_AFLAGS += -m64 -mcpu=ultrasparc
896 903
897 KBUILD_CFLAGS $(CC) compiler flags 904 KBUILD_CFLAGS $(CC) compiler flags
898 905
899 Default value - see top level Makefile 906 Default value - see top level Makefile
900 Append or modify as required per architecture. 907 Append or modify as required per architecture.
901 908
902 Often, the KBUILD_CFLAGS variable depends on the configuration. 909 Often, the KBUILD_CFLAGS variable depends on the configuration.
903 910
904 Example: 911 Example:
905 #arch/i386/Makefile 912 #arch/i386/Makefile
906 cflags-$(CONFIG_M386) += -march=i386 913 cflags-$(CONFIG_M386) += -march=i386
907 KBUILD_CFLAGS += $(cflags-y) 914 KBUILD_CFLAGS += $(cflags-y)
908 915
909 Many arch Makefiles dynamically run the target C compiler to 916 Many arch Makefiles dynamically run the target C compiler to
910 probe supported options: 917 probe supported options:
911 918
912 #arch/i386/Makefile 919 #arch/i386/Makefile
913 920
914 ... 921 ...
915 cflags-$(CONFIG_MPENTIUMII) += $(call cc-option,\ 922 cflags-$(CONFIG_MPENTIUMII) += $(call cc-option,\
916 -march=pentium2,-march=i686) 923 -march=pentium2,-march=i686)
917 ... 924 ...
918 # Disable unit-at-a-time mode ... 925 # Disable unit-at-a-time mode ...
919 KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time) 926 KBUILD_CFLAGS += $(call cc-option,-fno-unit-at-a-time)
920 ... 927 ...
921 928
922 929
923 The first example utilises the trick that a config option expands 930 The first example utilises the trick that a config option expands
924 to 'y' when selected. 931 to 'y' when selected.
925 932
926 CFLAGS_KERNEL $(CC) options specific for built-in 933 CFLAGS_KERNEL $(CC) options specific for built-in
927 934
928 $(CFLAGS_KERNEL) contains extra C compiler flags used to compile 935 $(CFLAGS_KERNEL) contains extra C compiler flags used to compile
929 resident kernel code. 936 resident kernel code.
930 937
931 CFLAGS_MODULE $(CC) options specific for modules 938 CFLAGS_MODULE $(CC) options specific for modules
932 939
933 $(CFLAGS_MODULE) contains extra C compiler flags used to compile code 940 $(CFLAGS_MODULE) contains extra C compiler flags used to compile code
934 for loadable kernel modules. 941 for loadable kernel modules.
935 942
936 943
937 --- 6.2 Add prerequisites to archprepare: 944 --- 6.2 Add prerequisites to archprepare:
938 945
939 The archprepare: rule is used to list prerequisites that need to be 946 The archprepare: rule is used to list prerequisites that need to be
940 built before starting to descend down in the subdirectories. 947 built before starting to descend down in the subdirectories.
941 This is usually used for header files containing assembler constants. 948 This is usually used for header files containing assembler constants.
942 949
943 Example: 950 Example:
944 #arch/arm/Makefile 951 #arch/arm/Makefile
945 archprepare: maketools 952 archprepare: maketools
946 953
947 In this example, the file target maketools will be processed 954 In this example, the file target maketools will be processed
948 before descending down in the subdirectories. 955 before descending down in the subdirectories.
949 See also chapter XXX-TODO that describe how kbuild supports 956 See also chapter XXX-TODO that describe how kbuild supports
950 generating offset header files. 957 generating offset header files.
951 958
952 959
953 --- 6.3 List directories to visit when descending 960 --- 6.3 List directories to visit when descending
954 961
955 An arch Makefile cooperates with the top Makefile to define variables 962 An arch Makefile cooperates with the top Makefile to define variables
956 which specify how to build the vmlinux file. Note that there is no 963 which specify how to build the vmlinux file. Note that there is no
957 corresponding arch-specific section for modules; the module-building 964 corresponding arch-specific section for modules; the module-building
958 machinery is all architecture-independent. 965 machinery is all architecture-independent.
959 966
960 967
961 head-y, init-y, core-y, libs-y, drivers-y, net-y 968 head-y, init-y, core-y, libs-y, drivers-y, net-y
962 969
963 $(head-y) lists objects to be linked first in vmlinux. 970 $(head-y) lists objects to be linked first in vmlinux.
964 $(libs-y) lists directories where a lib.a archive can be located. 971 $(libs-y) lists directories where a lib.a archive can be located.
965 The rest list directories where a built-in.o object file can be 972 The rest list directories where a built-in.o object file can be
966 located. 973 located.
967 974
968 $(init-y) objects will be located after $(head-y). 975 $(init-y) objects will be located after $(head-y).
969 Then the rest follows in this order: 976 Then the rest follows in this order:
970 $(core-y), $(libs-y), $(drivers-y) and $(net-y). 977 $(core-y), $(libs-y), $(drivers-y) and $(net-y).
971 978
972 The top level Makefile defines values for all generic directories, 979 The top level Makefile defines values for all generic directories,
973 and arch/$(ARCH)/Makefile only adds architecture-specific directories. 980 and arch/$(ARCH)/Makefile only adds architecture-specific directories.
974 981
975 Example: 982 Example:
976 #arch/sparc64/Makefile 983 #arch/sparc64/Makefile
977 core-y += arch/sparc64/kernel/ 984 core-y += arch/sparc64/kernel/
978 libs-y += arch/sparc64/prom/ arch/sparc64/lib/ 985 libs-y += arch/sparc64/prom/ arch/sparc64/lib/
979 drivers-$(CONFIG_OPROFILE) += arch/sparc64/oprofile/ 986 drivers-$(CONFIG_OPROFILE) += arch/sparc64/oprofile/
980 987
981 988
982 --- 6.4 Architecture-specific boot images 989 --- 6.4 Architecture-specific boot images
983 990
984 An arch Makefile specifies goals that take the vmlinux file, compress 991 An arch Makefile specifies goals that take the vmlinux file, compress
985 it, wrap it in bootstrapping code, and copy the resulting files 992 it, wrap it in bootstrapping code, and copy the resulting files
986 somewhere. This includes various kinds of installation commands. 993 somewhere. This includes various kinds of installation commands.
987 The actual goals are not standardized across architectures. 994 The actual goals are not standardized across architectures.
988 995
989 It is common to locate any additional processing in a boot/ 996 It is common to locate any additional processing in a boot/
990 directory below arch/$(ARCH)/. 997 directory below arch/$(ARCH)/.
991 998
992 Kbuild does not provide any smart way to support building a 999 Kbuild does not provide any smart way to support building a
993 target specified in boot/. Therefore arch/$(ARCH)/Makefile shall 1000 target specified in boot/. Therefore arch/$(ARCH)/Makefile shall
994 call make manually to build a target in boot/. 1001 call make manually to build a target in boot/.
995 1002
996 The recommended approach is to include shortcuts in 1003 The recommended approach is to include shortcuts in
997 arch/$(ARCH)/Makefile, and use the full path when calling down 1004 arch/$(ARCH)/Makefile, and use the full path when calling down
998 into the arch/$(ARCH)/boot/Makefile. 1005 into the arch/$(ARCH)/boot/Makefile.
999 1006
1000 Example: 1007 Example:
1001 #arch/i386/Makefile 1008 #arch/i386/Makefile
1002 boot := arch/i386/boot 1009 boot := arch/i386/boot
1003 bzImage: vmlinux 1010 bzImage: vmlinux
1004 $(Q)$(MAKE) $(build)=$(boot) $(boot)/$@ 1011 $(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
1005 1012
1006 "$(Q)$(MAKE) $(build)=<dir>" is the recommended way to invoke 1013 "$(Q)$(MAKE) $(build)=<dir>" is the recommended way to invoke
1007 make in a subdirectory. 1014 make in a subdirectory.
1008 1015
1009 There are no rules for naming architecture-specific targets, 1016 There are no rules for naming architecture-specific targets,
1010 but executing "make help" will list all relevant targets. 1017 but executing "make help" will list all relevant targets.
1011 To support this, $(archhelp) must be defined. 1018 To support this, $(archhelp) must be defined.
1012 1019
1013 Example: 1020 Example:
1014 #arch/i386/Makefile 1021 #arch/i386/Makefile
1015 define archhelp 1022 define archhelp
1016 echo '* bzImage - Image (arch/$(ARCH)/boot/bzImage)' 1023 echo '* bzImage - Image (arch/$(ARCH)/boot/bzImage)'
1017 endif 1024 endif
1018 1025
1019 When make is executed without arguments, the first goal encountered 1026 When make is executed without arguments, the first goal encountered
1020 will be built. In the top level Makefile the first goal present 1027 will be built. In the top level Makefile the first goal present
1021 is all:. 1028 is all:.
1022 An architecture shall always, per default, build a bootable image. 1029 An architecture shall always, per default, build a bootable image.
1023 In "make help", the default goal is highlighted with a '*'. 1030 In "make help", the default goal is highlighted with a '*'.
1024 Add a new prerequisite to all: to select a default goal different 1031 Add a new prerequisite to all: to select a default goal different
1025 from vmlinux. 1032 from vmlinux.
1026 1033
1027 Example: 1034 Example:
1028 #arch/i386/Makefile 1035 #arch/i386/Makefile
1029 all: bzImage 1036 all: bzImage
1030 1037
1031 When "make" is executed without arguments, bzImage will be built. 1038 When "make" is executed without arguments, bzImage will be built.
1032 1039
1033 --- 6.5 Building non-kbuild targets 1040 --- 6.5 Building non-kbuild targets
1034 1041
1035 extra-y 1042 extra-y
1036 1043
1037 extra-y specify additional targets created in the current 1044 extra-y specify additional targets created in the current
1038 directory, in addition to any targets specified by obj-*. 1045 directory, in addition to any targets specified by obj-*.
1039 1046
1040 Listing all targets in extra-y is required for two purposes: 1047 Listing all targets in extra-y is required for two purposes:
1041 1) Enable kbuild to check changes in command lines 1048 1) Enable kbuild to check changes in command lines
1042 - When $(call if_changed,xxx) is used 1049 - When $(call if_changed,xxx) is used
1043 2) kbuild knows what files to delete during "make clean" 1050 2) kbuild knows what files to delete during "make clean"
1044 1051
1045 Example: 1052 Example:
1046 #arch/i386/kernel/Makefile 1053 #arch/i386/kernel/Makefile
1047 extra-y := head.o init_task.o 1054 extra-y := head.o init_task.o
1048 1055
1049 In this example, extra-y is used to list object files that 1056 In this example, extra-y is used to list object files that
1050 shall be built, but shall not be linked as part of built-in.o. 1057 shall be built, but shall not be linked as part of built-in.o.
1051 1058
1052 1059
1053 --- 6.6 Commands useful for building a boot image 1060 --- 6.6 Commands useful for building a boot image
1054 1061
1055 Kbuild provides a few macros that are useful when building a 1062 Kbuild provides a few macros that are useful when building a
1056 boot image. 1063 boot image.
1057 1064
1058 if_changed 1065 if_changed
1059 1066
1060 if_changed is the infrastructure used for the following commands. 1067 if_changed is the infrastructure used for the following commands.
1061 1068
1062 Usage: 1069 Usage:
1063 target: source(s) FORCE 1070 target: source(s) FORCE
1064 $(call if_changed,ld/objcopy/gzip) 1071 $(call if_changed,ld/objcopy/gzip)
1065 1072
1066 When the rule is evaluated, it is checked to see if any files 1073 When the rule is evaluated, it is checked to see if any files
1067 need an update, or the command line has changed since the last 1074 need an update, or the command line has changed since the last
1068 invocation. The latter will force a rebuild if any options 1075 invocation. The latter will force a rebuild if any options
1069 to the executable have changed. 1076 to the executable have changed.
1070 Any target that utilises if_changed must be listed in $(targets), 1077 Any target that utilises if_changed must be listed in $(targets),
1071 otherwise the command line check will fail, and the target will 1078 otherwise the command line check will fail, and the target will
1072 always be built. 1079 always be built.
1073 Assignments to $(targets) are without $(obj)/ prefix. 1080 Assignments to $(targets) are without $(obj)/ prefix.
1074 if_changed may be used in conjunction with custom commands as 1081 if_changed may be used in conjunction with custom commands as
1075 defined in 6.7 "Custom kbuild commands". 1082 defined in 6.7 "Custom kbuild commands".
1076 1083
1077 Note: It is a typical mistake to forget the FORCE prerequisite. 1084 Note: It is a typical mistake to forget the FORCE prerequisite.
1078 Another common pitfall is that whitespace is sometimes 1085 Another common pitfall is that whitespace is sometimes
1079 significant; for instance, the below will fail (note the extra space 1086 significant; for instance, the below will fail (note the extra space
1080 after the comma): 1087 after the comma):
1081 target: source(s) FORCE 1088 target: source(s) FORCE
1082 #WRONG!# $(call if_changed, ld/objcopy/gzip) 1089 #WRONG!# $(call if_changed, ld/objcopy/gzip)
1083 1090
1084 ld 1091 ld
1085 Link target. Often, LDFLAGS_$@ is used to set specific options to ld. 1092 Link target. Often, LDFLAGS_$@ is used to set specific options to ld.
1086 1093
1087 objcopy 1094 objcopy
1088 Copy binary. Uses OBJCOPYFLAGS usually specified in 1095 Copy binary. Uses OBJCOPYFLAGS usually specified in
1089 arch/$(ARCH)/Makefile. 1096 arch/$(ARCH)/Makefile.
1090 OBJCOPYFLAGS_$@ may be used to set additional options. 1097 OBJCOPYFLAGS_$@ may be used to set additional options.
1091 1098
1092 gzip 1099 gzip
1093 Compress target. Use maximum compression to compress target. 1100 Compress target. Use maximum compression to compress target.
1094 1101
1095 Example: 1102 Example:
1096 #arch/i386/boot/Makefile 1103 #arch/i386/boot/Makefile
1097 LDFLAGS_bootsect := -Ttext 0x0 -s --oformat binary 1104 LDFLAGS_bootsect := -Ttext 0x0 -s --oformat binary
1098 LDFLAGS_setup := -Ttext 0x0 -s --oformat binary -e begtext 1105 LDFLAGS_setup := -Ttext 0x0 -s --oformat binary -e begtext
1099 1106
1100 targets += setup setup.o bootsect bootsect.o 1107 targets += setup setup.o bootsect bootsect.o
1101 $(obj)/setup $(obj)/bootsect: %: %.o FORCE 1108 $(obj)/setup $(obj)/bootsect: %: %.o FORCE
1102 $(call if_changed,ld) 1109 $(call if_changed,ld)
1103 1110
1104 In this example, there are two possible targets, requiring different 1111 In this example, there are two possible targets, requiring different
1105 options to the linker. The linker options are specified using the 1112 options to the linker. The linker options are specified using the
1106 LDFLAGS_$@ syntax - one for each potential target. 1113 LDFLAGS_$@ syntax - one for each potential target.
1107 $(targets) are assigned all potential targets, by which kbuild knows 1114 $(targets) are assigned all potential targets, by which kbuild knows
1108 the targets and will: 1115 the targets and will:
1109 1) check for commandline changes 1116 1) check for commandline changes
1110 2) delete target during make clean 1117 2) delete target during make clean
1111 1118
1112 The ": %: %.o" part of the prerequisite is a shorthand that 1119 The ": %: %.o" part of the prerequisite is a shorthand that
1113 free us from listing the setup.o and bootsect.o files. 1120 free us from listing the setup.o and bootsect.o files.
1114 Note: It is a common mistake to forget the "target :=" assignment, 1121 Note: It is a common mistake to forget the "target :=" assignment,
1115 resulting in the target file being recompiled for no 1122 resulting in the target file being recompiled for no
1116 obvious reason. 1123 obvious reason.
1117 1124
1118 1125
1119 --- 6.7 Custom kbuild commands 1126 --- 6.7 Custom kbuild commands
1120 1127
1121 When kbuild is executing with KBUILD_VERBOSE=0, then only a shorthand 1128 When kbuild is executing with KBUILD_VERBOSE=0, then only a shorthand
1122 of a command is normally displayed. 1129 of a command is normally displayed.
1123 To enable this behaviour for custom commands kbuild requires 1130 To enable this behaviour for custom commands kbuild requires
1124 two variables to be set: 1131 two variables to be set:
1125 quiet_cmd_<command> - what shall be echoed 1132 quiet_cmd_<command> - what shall be echoed
1126 cmd_<command> - the command to execute 1133 cmd_<command> - the command to execute
1127 1134
1128 Example: 1135 Example:
1129 # 1136 #
1130 quiet_cmd_image = BUILD $@ 1137 quiet_cmd_image = BUILD $@
1131 cmd_image = $(obj)/tools/build $(BUILDFLAGS) \ 1138 cmd_image = $(obj)/tools/build $(BUILDFLAGS) \
1132 $(obj)/vmlinux.bin > $@ 1139 $(obj)/vmlinux.bin > $@
1133 1140
1134 targets += bzImage 1141 targets += bzImage
1135 $(obj)/bzImage: $(obj)/vmlinux.bin $(obj)/tools/build FORCE 1142 $(obj)/bzImage: $(obj)/vmlinux.bin $(obj)/tools/build FORCE
1136 $(call if_changed,image) 1143 $(call if_changed,image)
1137 @echo 'Kernel: $@ is ready' 1144 @echo 'Kernel: $@ is ready'
1138 1145
1139 When updating the $(obj)/bzImage target, the line 1146 When updating the $(obj)/bzImage target, the line
1140 1147
1141 BUILD arch/i386/boot/bzImage 1148 BUILD arch/i386/boot/bzImage
1142 1149
1143 will be displayed with "make KBUILD_VERBOSE=0". 1150 will be displayed with "make KBUILD_VERBOSE=0".
1144 1151
1145 1152
1146 --- 6.8 Preprocessing linker scripts 1153 --- 6.8 Preprocessing linker scripts
1147 1154
1148 When the vmlinux image is built, the linker script 1155 When the vmlinux image is built, the linker script
1149 arch/$(ARCH)/kernel/vmlinux.lds is used. 1156 arch/$(ARCH)/kernel/vmlinux.lds is used.
1150 The script is a preprocessed variant of the file vmlinux.lds.S 1157 The script is a preprocessed variant of the file vmlinux.lds.S
1151 located in the same directory. 1158 located in the same directory.
1152 kbuild knows .lds files and includes a rule *lds.S -> *lds. 1159 kbuild knows .lds files and includes a rule *lds.S -> *lds.
1153 1160
1154 Example: 1161 Example:
1155 #arch/i386/kernel/Makefile 1162 #arch/i386/kernel/Makefile
1156 always := vmlinux.lds 1163 always := vmlinux.lds
1157 1164
1158 #Makefile 1165 #Makefile
1159 export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH) 1166 export CPPFLAGS_vmlinux.lds += -P -C -U$(ARCH)
1160 1167
1161 The assignment to $(always) is used to tell kbuild to build the 1168 The assignment to $(always) is used to tell kbuild to build the
1162 target vmlinux.lds. 1169 target vmlinux.lds.
1163 The assignment to $(CPPFLAGS_vmlinux.lds) tells kbuild to use the 1170 The assignment to $(CPPFLAGS_vmlinux.lds) tells kbuild to use the
1164 specified options when building the target vmlinux.lds. 1171 specified options when building the target vmlinux.lds.
1165 1172
1166 When building the *.lds target, kbuild uses the variables: 1173 When building the *.lds target, kbuild uses the variables:
1167 KBUILD_CPPFLAGS : Set in top-level Makefile 1174 KBUILD_CPPFLAGS : Set in top-level Makefile
1168 cppflags-y : May be set in the kbuild makefile 1175 cppflags-y : May be set in the kbuild makefile
1169 CPPFLAGS_$(@F) : Target specific flags. 1176 CPPFLAGS_$(@F) : Target specific flags.
1170 Note that the full filename is used in this 1177 Note that the full filename is used in this
1171 assignment. 1178 assignment.
1172 1179
1173 The kbuild infrastructure for *lds file are used in several 1180 The kbuild infrastructure for *lds file are used in several
1174 architecture-specific files. 1181 architecture-specific files.
1175 1182
1176 === 7 Kbuild syntax for exported headers 1183 === 7 Kbuild syntax for exported headers
1177 1184
1178 The kernel include a set of headers that is exported to userspace. 1185 The kernel include a set of headers that is exported to userspace.
1179 Many headers can be exported as-is but other headers requires a 1186 Many headers can be exported as-is but other headers requires a
1180 minimal pre-processing before they are ready for user-space. 1187 minimal pre-processing before they are ready for user-space.
1181 The pre-processing does: 1188 The pre-processing does:
1182 - drop kernel specific annotations 1189 - drop kernel specific annotations
1183 - drop include of compiler.h 1190 - drop include of compiler.h
1184 - drop all sections that is kernel internat (guarded by ifdef __KERNEL__) 1191 - drop all sections that is kernel internat (guarded by ifdef __KERNEL__)
1185 1192
1186 Each relevant directory contain a file name "Kbuild" which specify the 1193 Each relevant directory contain a file name "Kbuild" which specify the
1187 headers to be exported. 1194 headers to be exported.
1188 See subsequent chapter for the syntax of the Kbuild file. 1195 See subsequent chapter for the syntax of the Kbuild file.
1189 1196
1190 --- 7.1 header-y 1197 --- 7.1 header-y
1191 1198
1192 header-y specify header files to be exported. 1199 header-y specify header files to be exported.
1193 1200
1194 Example: 1201 Example:
1195 #include/linux/Kbuild 1202 #include/linux/Kbuild
1196 header-y += usb/ 1203 header-y += usb/
1197 header-y += aio_abi.h 1204 header-y += aio_abi.h
1198 1205
1199 The convention is to list one file per line and 1206 The convention is to list one file per line and
1200 preferably in alphabetic order. 1207 preferably in alphabetic order.
1201 1208
1202 header-y also specify which subdirectories to visit. 1209 header-y also specify which subdirectories to visit.
1203 A subdirectory is identified by a trailing '/' which 1210 A subdirectory is identified by a trailing '/' which
1204 can be seen in the example above for the usb subdirectory. 1211 can be seen in the example above for the usb subdirectory.
1205 1212
1206 Subdirectories are visited before their parent directories. 1213 Subdirectories are visited before their parent directories.
1207 1214
1208 --- 7.2 objhdr-y 1215 --- 7.2 objhdr-y
1209 1216
1210 objhdr-y specifies generated files to be exported. 1217 objhdr-y specifies generated files to be exported.
1211 Generated files are special as they need to be looked 1218 Generated files are special as they need to be looked
1212 up in another directory when doing 'make O=...' builds. 1219 up in another directory when doing 'make O=...' builds.
1213 1220
1214 Example: 1221 Example:
1215 #include/linux/Kbuild 1222 #include/linux/Kbuild
1216 objhdr-y += version.h 1223 objhdr-y += version.h
1217 1224
1218 --- 7.3 destination-y 1225 --- 7.3 destination-y
1219 1226
1220 When an architecture have a set of exported headers that needs to be 1227 When an architecture have a set of exported headers that needs to be
1221 exported to a different directory destination-y is used. 1228 exported to a different directory destination-y is used.
1222 destination-y specify the destination directory for all exported 1229 destination-y specify the destination directory for all exported
1223 headers in the file where it is present. 1230 headers in the file where it is present.
1224 1231
1225 Example: 1232 Example:
1226 #arch/xtensa/platforms/s6105/include/platform/Kbuild 1233 #arch/xtensa/platforms/s6105/include/platform/Kbuild
1227 destination-y := include/linux 1234 destination-y := include/linux
1228 1235
1229 In the example above all exported headers in the Kbuild file 1236 In the example above all exported headers in the Kbuild file
1230 will be located in the directory "include/linux" when exported. 1237 will be located in the directory "include/linux" when exported.
1231 1238
1232 1239
1233 --- 7.4 unifdef-y (deprecated) 1240 --- 7.4 unifdef-y (deprecated)
1234 1241
1235 unifdef-y is deprecated. A direct replacement is header-y. 1242 unifdef-y is deprecated. A direct replacement is header-y.
1236 1243
1237 1244
1238 === 8 Kbuild Variables 1245 === 8 Kbuild Variables
1239 1246
1240 The top Makefile exports the following variables: 1247 The top Makefile exports the following variables:
1241 1248
1242 VERSION, PATCHLEVEL, SUBLEVEL, EXTRAVERSION 1249 VERSION, PATCHLEVEL, SUBLEVEL, EXTRAVERSION
1243 1250
1244 These variables define the current kernel version. A few arch 1251 These variables define the current kernel version. A few arch
1245 Makefiles actually use these values directly; they should use 1252 Makefiles actually use these values directly; they should use
1246 $(KERNELRELEASE) instead. 1253 $(KERNELRELEASE) instead.
1247 1254
1248 $(VERSION), $(PATCHLEVEL), and $(SUBLEVEL) define the basic 1255 $(VERSION), $(PATCHLEVEL), and $(SUBLEVEL) define the basic
1249 three-part version number, such as "2", "4", and "0". These three 1256 three-part version number, such as "2", "4", and "0". These three
1250 values are always numeric. 1257 values are always numeric.
1251 1258
1252 $(EXTRAVERSION) defines an even tinier sublevel for pre-patches 1259 $(EXTRAVERSION) defines an even tinier sublevel for pre-patches
1253 or additional patches. It is usually some non-numeric string 1260 or additional patches. It is usually some non-numeric string
1254 such as "-pre4", and is often blank. 1261 such as "-pre4", and is often blank.
1255 1262
1256 KERNELRELEASE 1263 KERNELRELEASE
1257 1264
1258 $(KERNELRELEASE) is a single string such as "2.4.0-pre4", suitable 1265 $(KERNELRELEASE) is a single string such as "2.4.0-pre4", suitable
1259 for constructing installation directory names or showing in 1266 for constructing installation directory names or showing in
1260 version strings. Some arch Makefiles use it for this purpose. 1267 version strings. Some arch Makefiles use it for this purpose.
1261 1268
1262 ARCH 1269 ARCH
1263 1270
1264 This variable defines the target architecture, such as "i386", 1271 This variable defines the target architecture, such as "i386",
1265 "arm", or "sparc". Some kbuild Makefiles test $(ARCH) to 1272 "arm", or "sparc". Some kbuild Makefiles test $(ARCH) to
1266 determine which files to compile. 1273 determine which files to compile.
1267 1274
1268 By default, the top Makefile sets $(ARCH) to be the same as the 1275 By default, the top Makefile sets $(ARCH) to be the same as the
1269 host system architecture. For a cross build, a user may 1276 host system architecture. For a cross build, a user may
1270 override the value of $(ARCH) on the command line: 1277 override the value of $(ARCH) on the command line:
1271 1278
1272 make ARCH=m68k ... 1279 make ARCH=m68k ...
1273 1280
1274 1281
1275 INSTALL_PATH 1282 INSTALL_PATH
1276 1283
1277 This variable defines a place for the arch Makefiles to install 1284 This variable defines a place for the arch Makefiles to install
1278 the resident kernel image and System.map file. 1285 the resident kernel image and System.map file.
1279 Use this for architecture-specific install targets. 1286 Use this for architecture-specific install targets.
1280 1287
1281 INSTALL_MOD_PATH, MODLIB 1288 INSTALL_MOD_PATH, MODLIB
1282 1289
1283 $(INSTALL_MOD_PATH) specifies a prefix to $(MODLIB) for module 1290 $(INSTALL_MOD_PATH) specifies a prefix to $(MODLIB) for module
1284 installation. This variable is not defined in the Makefile but 1291 installation. This variable is not defined in the Makefile but
1285 may be passed in by the user if desired. 1292 may be passed in by the user if desired.
1286 1293
1287 $(MODLIB) specifies the directory for module installation. 1294 $(MODLIB) specifies the directory for module installation.
1288 The top Makefile defines $(MODLIB) to 1295 The top Makefile defines $(MODLIB) to
1289 $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE). The user may 1296 $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE). The user may
1290 override this value on the command line if desired. 1297 override this value on the command line if desired.
1291 1298
1292 INSTALL_MOD_STRIP 1299 INSTALL_MOD_STRIP
1293 1300
1294 If this variable is specified, will cause modules to be stripped 1301 If this variable is specified, will cause modules to be stripped
1295 after they are installed. If INSTALL_MOD_STRIP is '1', then the 1302 after they are installed. If INSTALL_MOD_STRIP is '1', then the
1296 default option --strip-debug will be used. Otherwise, 1303 default option --strip-debug will be used. Otherwise,
1297 INSTALL_MOD_STRIP will used as the option(s) to the strip command. 1304 INSTALL_MOD_STRIP will used as the option(s) to the strip command.
1298 1305
1299 1306
1300 === 9 Makefile language 1307 === 9 Makefile language
1301 1308
1302 The kernel Makefiles are designed to be run with GNU Make. The Makefiles 1309 The kernel Makefiles are designed to be run with GNU Make. The Makefiles
1303 use only the documented features of GNU Make, but they do use many 1310 use only the documented features of GNU Make, but they do use many
1304 GNU extensions. 1311 GNU extensions.
1305 1312
1306 GNU Make supports elementary list-processing functions. The kernel 1313 GNU Make supports elementary list-processing functions. The kernel
1307 Makefiles use a novel style of list building and manipulation with few 1314 Makefiles use a novel style of list building and manipulation with few
1308 "if" statements. 1315 "if" statements.
1309 1316
1310 GNU Make has two assignment operators, ":=" and "=". ":=" performs 1317 GNU Make has two assignment operators, ":=" and "=". ":=" performs
1311 immediate evaluation of the right-hand side and stores an actual string 1318 immediate evaluation of the right-hand side and stores an actual string
1312 into the left-hand side. "=" is like a formula definition; it stores the 1319 into the left-hand side. "=" is like a formula definition; it stores the
1313 right-hand side in an unevaluated form and then evaluates this form each 1320 right-hand side in an unevaluated form and then evaluates this form each
1314 time the left-hand side is used. 1321 time the left-hand side is used.
1315 1322
1316 There are some cases where "=" is appropriate. Usually, though, ":=" 1323 There are some cases where "=" is appropriate. Usually, though, ":="
1317 is the right choice. 1324 is the right choice.
1318 1325
1319 === 10 Credits 1326 === 10 Credits
1320 1327
1321 Original version made by Michael Elizabeth Chastain, <mailto:mec@shout.net> 1328 Original version made by Michael Elizabeth Chastain, <mailto:mec@shout.net>
1322 Updates by Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de> 1329 Updates by Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de>
1323 Updates by Sam Ravnborg <sam@ravnborg.org> 1330 Updates by Sam Ravnborg <sam@ravnborg.org>
1324 Language QA by Jan Engelhardt <jengelh@gmx.de> 1331 Language QA by Jan Engelhardt <jengelh@gmx.de>
1325 1332
1326 === 11 TODO 1333 === 11 TODO
1327 1334
1328 - Describe how kbuild supports shipped files with _shipped. 1335 - Describe how kbuild supports shipped files with _shipped.
1329 - Generating offset header files. 1336 - Generating offset header files.
1330 - Add more variables to section 7? 1337 - Add more variables to section 7?
1331 1338
1332 1339
1333 1340
1334 1341
1 # 1 #
2 # Kbuild for top-level directory of the kernel 2 # Kbuild for top-level directory of the kernel
3 # This file takes care of the following: 3 # This file takes care of the following:
4 # 1) Generate bounds.h 4 # 1) Generate bounds.h
5 # 2) Generate asm-offsets.h (may need bounds.h) 5 # 2) Generate asm-offsets.h (may need bounds.h)
6 # 3) Check for missing system calls 6 # 3) Check for missing system calls
7 7
8 ##### 8 #####
9 # 1) Generate bounds.h 9 # 1) Generate bounds.h
10 10
11 bounds-file := include/generated/bounds.h 11 bounds-file := include/generated/bounds.h
12 12
13 always := $(bounds-file) 13 always := $(bounds-file)
14 targets := $(bounds-file) kernel/bounds.s 14 targets := $(bounds-file) kernel/bounds.s
15 15
16 quiet_cmd_bounds = GEN $@ 16 quiet_cmd_bounds = GEN $@
17 define cmd_bounds 17 define cmd_bounds
18 (set -e; \ 18 (set -e; \
19 echo "#ifndef __LINUX_BOUNDS_H__"; \ 19 echo "#ifndef __LINUX_BOUNDS_H__"; \
20 echo "#define __LINUX_BOUNDS_H__"; \ 20 echo "#define __LINUX_BOUNDS_H__"; \
21 echo "/*"; \ 21 echo "/*"; \
22 echo " * DO NOT MODIFY."; \ 22 echo " * DO NOT MODIFY."; \
23 echo " *"; \ 23 echo " *"; \
24 echo " * This file was generated by Kbuild"; \ 24 echo " * This file was generated by Kbuild"; \
25 echo " *"; \ 25 echo " *"; \
26 echo " */"; \ 26 echo " */"; \
27 echo ""; \ 27 echo ""; \
28 sed -ne $(sed-y) $<; \ 28 sed -ne $(sed-y) $<; \
29 echo ""; \ 29 echo ""; \
30 echo "#endif" ) > $@ 30 echo "#endif" ) > $@
31 endef 31 endef
32 32
33 # We use internal kbuild rules to avoid the "is up to date" message from make 33 # We use internal kbuild rules to avoid the "is up to date" message from make
34 kernel/bounds.s: kernel/bounds.c FORCE 34 kernel/bounds.s: kernel/bounds.c FORCE
35 $(Q)mkdir -p $(dir $@) 35 $(Q)mkdir -p $(dir $@)
36 $(call if_changed_dep,cc_s_c) 36 $(call if_changed_dep,cc_s_c)
37 37
38 $(obj)/$(bounds-file): kernel/bounds.s Kbuild 38 $(obj)/$(bounds-file): kernel/bounds.s Kbuild
39 $(Q)mkdir -p $(dir $@) 39 $(Q)mkdir -p $(dir $@)
40 $(call cmd,bounds) 40 $(call cmd,bounds)
41 41
42 ##### 42 #####
43 # 2) Generate asm-offsets.h 43 # 2) Generate asm-offsets.h
44 # 44 #
45 45
46 offsets-file := include/generated/asm-offsets.h 46 offsets-file := include/generated/asm-offsets.h
47 47
48 always += $(offsets-file) 48 always += $(offsets-file)
49 targets += $(offsets-file) 49 targets += $(offsets-file)
50 targets += arch/$(SRCARCH)/kernel/asm-offsets.s 50 targets += arch/$(SRCARCH)/kernel/asm-offsets.s
51 51
52 52
53 # Default sed regexp - multiline due to syntax constraints 53 # Default sed regexp - multiline due to syntax constraints
54 define sed-y 54 define sed-y
55 "/^->/{s:->#\(.*\):/* \1 */:; \ 55 "/^->/{s:->#\(.*\):/* \1 */:; \
56 s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \ 56 s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
57 s:->::; p;}" 57 s:->::; p;}"
58 endef 58 endef
59 59
60 quiet_cmd_offsets = GEN $@ 60 quiet_cmd_offsets = GEN $@
61 define cmd_offsets 61 define cmd_offsets
62 (set -e; \ 62 (set -e; \
63 echo "#ifndef __ASM_OFFSETS_H__"; \ 63 echo "#ifndef __ASM_OFFSETS_H__"; \
64 echo "#define __ASM_OFFSETS_H__"; \ 64 echo "#define __ASM_OFFSETS_H__"; \
65 echo "/*"; \ 65 echo "/*"; \
66 echo " * DO NOT MODIFY."; \ 66 echo " * DO NOT MODIFY."; \
67 echo " *"; \ 67 echo " *"; \
68 echo " * This file was generated by Kbuild"; \ 68 echo " * This file was generated by Kbuild"; \
69 echo " *"; \ 69 echo " *"; \
70 echo " */"; \ 70 echo " */"; \
71 echo ""; \ 71 echo ""; \
72 sed -ne $(sed-y) $<; \ 72 sed -ne $(sed-y) $<; \
73 echo ""; \ 73 echo ""; \
74 echo "#endif" ) > $@ 74 echo "#endif" ) > $@
75 endef 75 endef
76 76
77 # We use internal kbuild rules to avoid the "is up to date" message from make 77 # We use internal kbuild rules to avoid the "is up to date" message from make
78 arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \ 78 arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
79 $(obj)/$(bounds-file) FORCE 79 $(obj)/$(bounds-file) FORCE
80 $(Q)mkdir -p $(dir $@) 80 $(Q)mkdir -p $(dir $@)
81 $(call if_changed_dep,cc_s_c) 81 $(call if_changed_dep,cc_s_c)
82 82
83 $(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild 83 $(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
84 $(call cmd,offsets) 84 $(call cmd,offsets)
85 85
86 ##### 86 #####
87 # 3) Check for missing system calls 87 # 3) Check for missing system calls
88 # 88 #
89 89
90 quiet_cmd_syscalls = CALL $< 90 quiet_cmd_syscalls = CALL $<
91 cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) 91 cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags)
92 92
93 PHONY += missing-syscalls 93 PHONY += missing-syscalls
94 missing-syscalls: scripts/checksyscalls.sh FORCE 94 missing-syscalls: scripts/checksyscalls.sh FORCE
95 $(call cmd,syscalls) 95 $(call cmd,syscalls)
96 96
97 # Delete all targets during make clean 97 # Keep these two files during make clean
98 clean-files := $(addprefix $(objtree)/,$(filter-out $(bounds-file) $(offsets-file),$(targets))) 98 no-clean-files := $(bounds-file) $(offsets-file)
99 99
scripts/Makefile.clean
Diff comments   View file @ ef8ff89
1 # ========================================================================== 1 # ==========================================================================
2 # Cleaning up 2 # Cleaning up
3 # ========================================================================== 3 # ==========================================================================
4 4
5 src := $(obj) 5 src := $(obj)
6 6
7 PHONY := __clean 7 PHONY := __clean
8 __clean: 8 __clean:
9 9
10 # Shorthand for $(Q)$(MAKE) scripts/Makefile.clean obj=dir 10 # Shorthand for $(Q)$(MAKE) scripts/Makefile.clean obj=dir
11 # Usage: 11 # Usage:
12 # $(Q)$(MAKE) $(clean)=dir 12 # $(Q)$(MAKE) $(clean)=dir
13 clean := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.clean obj 13 clean := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.clean obj
14 14
15 # The filename Kbuild has precedence over Makefile 15 # The filename Kbuild has precedence over Makefile
16 kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src)) 16 kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
17 include $(if $(wildcard $(kbuild-dir)/Kbuild), $(kbuild-dir)/Kbuild, $(kbuild-dir)/Makefile) 17 include $(if $(wildcard $(kbuild-dir)/Kbuild), $(kbuild-dir)/Kbuild, $(kbuild-dir)/Makefile)
18 18
19 # Figure out what we need to build from the various variables 19 # Figure out what we need to build from the various variables
20 # ========================================================================== 20 # ==========================================================================
21 21
22 __subdir-y := $(patsubst %/,%,$(filter %/, $(obj-y))) 22 __subdir-y := $(patsubst %/,%,$(filter %/, $(obj-y)))
23 subdir-y += $(__subdir-y) 23 subdir-y += $(__subdir-y)
24 __subdir-m := $(patsubst %/,%,$(filter %/, $(obj-m))) 24 __subdir-m := $(patsubst %/,%,$(filter %/, $(obj-m)))
25 subdir-m += $(__subdir-m) 25 subdir-m += $(__subdir-m)
26 __subdir-n := $(patsubst %/,%,$(filter %/, $(obj-n))) 26 __subdir-n := $(patsubst %/,%,$(filter %/, $(obj-n)))
27 subdir-n += $(__subdir-n) 27 subdir-n += $(__subdir-n)
28 __subdir- := $(patsubst %/,%,$(filter %/, $(obj-))) 28 __subdir- := $(patsubst %/,%,$(filter %/, $(obj-)))
29 subdir- += $(__subdir-) 29 subdir- += $(__subdir-)
30 30
31 # Subdirectories we need to descend into 31 # Subdirectories we need to descend into
32 32
33 subdir-ym := $(sort $(subdir-y) $(subdir-m)) 33 subdir-ym := $(sort $(subdir-y) $(subdir-m))
34 subdir-ymn := $(sort $(subdir-ym) $(subdir-n) $(subdir-)) 34 subdir-ymn := $(sort $(subdir-ym) $(subdir-n) $(subdir-))
35 35
36 # Add subdir path 36 # Add subdir path
37 37
38 subdir-ymn := $(addprefix $(obj)/,$(subdir-ymn)) 38 subdir-ymn := $(addprefix $(obj)/,$(subdir-ymn))
39 39
40 # build a list of files to remove, usually relative to the current 40 # build a list of files to remove, usually relative to the current
41 # directory 41 # directory
42 42
43 __clean-files := $(extra-y) $(always) \ 43 __clean-files := $(extra-y) $(always) \
44 $(targets) $(clean-files) \ 44 $(targets) $(clean-files) \
45 $(host-progs) \ 45 $(host-progs) \
46 $(hostprogs-y) $(hostprogs-m) $(hostprogs-) 46 $(hostprogs-y) $(hostprogs-m) $(hostprogs-)
47 47
48 __clean-files := $(filter-out $(no-clean-files), $(__clean-files))
49
48 # as clean-files is given relative to the current directory, this adds 50 # as clean-files is given relative to the current directory, this adds
49 # a $(obj) prefix, except for absolute paths 51 # a $(obj) prefix, except for absolute paths
50 52
51 __clean-files := $(wildcard \ 53 __clean-files := $(wildcard \
52 $(addprefix $(obj)/, $(filter-out /%, $(__clean-files))) \ 54 $(addprefix $(obj)/, $(filter-out /%, $(__clean-files))) \
53 $(filter /%, $(__clean-files))) 55 $(filter /%, $(__clean-files)))
54 56
55 # as clean-dirs is given relative to the current directory, this adds 57 # as clean-dirs is given relative to the current directory, this adds
56 # a $(obj) prefix, except for absolute paths 58 # a $(obj) prefix, except for absolute paths
57 59
58 __clean-dirs := $(wildcard \ 60 __clean-dirs := $(wildcard \
59 $(addprefix $(obj)/, $(filter-out /%, $(clean-dirs))) \ 61 $(addprefix $(obj)/, $(filter-out /%, $(clean-dirs))) \
60 $(filter /%, $(clean-dirs))) 62 $(filter /%, $(clean-dirs)))
61 63
62 # ========================================================================== 64 # ==========================================================================
63 65
64 quiet_cmd_clean = CLEAN $(obj) 66 quiet_cmd_clean = CLEAN $(obj)
65 cmd_clean = rm -f $(__clean-files) 67 cmd_clean = rm -f $(__clean-files)
66 quiet_cmd_cleandir = CLEAN $(__clean-dirs) 68 quiet_cmd_cleandir = CLEAN $(__clean-dirs)
67 cmd_cleandir = rm -rf $(__clean-dirs) 69 cmd_cleandir = rm -rf $(__clean-dirs)
68 70
69 71
70 __clean: $(subdir-ymn) 72 __clean: $(subdir-ymn)
71 ifneq ($(strip $(__clean-files)),) 73 ifneq ($(strip $(__clean-files)),)
72 +$(call cmd,clean) 74 +$(call cmd,clean)
73 endif 75 endif
74 ifneq ($(strip $(__clean-dirs)),) 76 ifneq ($(strip $(__clean-dirs)),)
75 +$(call cmd,cleandir) 77 +$(call cmd,cleandir)
76 endif 78 endif
77 ifneq ($(strip $(clean-rule)),) 79 ifneq ($(strip $(clean-rule)),)
78 +$(clean-rule) 80 +$(clean-rule)
79 endif 81 endif
80 @: 82 @:
81 83
82 84
83 # =========================================================================== 85 # ===========================================================================
84 # Generic stuff 86 # Generic stuff
85 # =========================================================================== 87 # ===========================================================================
86 88
87 # Descending 89 # Descending
88 # --------------------------------------------------------------------------- 90 # ---------------------------------------------------------------------------
89 91
90 PHONY += $(subdir-ymn) 92 PHONY += $(subdir-ymn)
91 $(subdir-ymn): 93 $(subdir-ymn):
92 $(Q)$(MAKE) $(clean)=$@ 94 $(Q)$(MAKE) $(clean)=$@
93 95
94 # If quiet is set, only print short version of command 96 # If quiet is set, only print short version of command
95 97
96 cmd = @$(if $($(quiet)cmd_$(1)),echo ' $($(quiet)cmd_$(1))' &&) $(cmd_$(1)) 98 cmd = @$(if $($(quiet)cmd_$(1)),echo ' $($(quiet)cmd_$(1))' &&) $(cmd_$(1))
97 99
98 100
99 # Declare the contents of the .PHONY variable as phony. We keep that 101 # Declare the contents of the .PHONY variable as phony. We keep that
100 # information in a variable se we can use it in if_changed and friends. 102 # information in a variable se we can use it in if_changed and friends.
101 103
102 .PHONY: $(PHONY) 104 .PHONY: $(PHONY)
103 105