x86: remove zImage support

Impact: obsolete feature removal The zImage kernel format has been functionally unused for a very long time. It is just barely possible to build a modern kernel that still fits within the zImage size limit, but it is highly unlikely that anyone ever uses it. Furthermore, although it is still supported by most bootloaders, it has been at best poorly tested (or not tested at all); some bootloaders are even known to not support zImage at all and not having even noticed. Also remove some really obsolete constants that no longer have any meaning. LKML-Reference: <49B703D4.1000008@zytor.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>

x86: remove zImage support
Impact: obsolete feature removal The zImage kernel format has been functionally unused for a very long time. It is just barely possible to build a modern kernel that still fits within the zImage size limit, but it is highly unlikely that anyone ever uses it. Furthermore, although it is still supported by most bootloaders, it has been at best poorly tested (or not tested at all); some bootloaders are even known to not support zImage at all and not having even noticed. Also remove some really obsolete constants that no longer have any meaning. LKML-Reference: <49B703D4.1000008@zytor.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
H. Peter Anvin · Eric Lee · Eric Lee · Eric Lee · Eric Lee · Eric Lee
1 parent 78b020d035
Showing 5 changed files with 18 additions and 91 deletions Side-by-side Diff
arch/x86/boot/Makefile
arch/x86/boot/header.S
arch/x86/boot/pm.c
arch/x86/boot/tools/build.c
arch/x86/include/asm/boot.h
@@ -6,26 +6,23 @@
 # for more details.
 #
 # Copyright (C) 1994 by Linus Torvalds
+# Changed by many, many contributors over the years.
 #
  
 # ROOT_DEV specifies the default root-device when making the image.
 # This can be either FLOPPY, CURRENT, /dev/xxxx or empty, in which case
 # the default of FLOPPY is used by 'build'.
  
-ROOT_DEV := CURRENT
+ROOT_DEV	:= CURRENT
  
 # If you want to preset the SVGA mode, uncomment the next line and
 # set SVGA_MODE to whatever number you want.
 # Set it to -DSVGA_MODE=NORMAL_VGA if you just want the EGA/VGA mode.
 # The number is the same as you would ordinarily press at bootup.
  
-SVGA_MODE := -DSVGA_MODE=NORMAL_VGA
+SVGA_MODE	:= -DSVGA_MODE=NORMAL_VGA
  
-# If you want the RAM disk device, define this to be the size in blocks.
-
-#RAMDISK := -DRAMDISK=512
-
-targets		:= vmlinux.bin setup.bin setup.elf zImage bzImage
+targets		:= vmlinux.bin setup.bin setup.elf bzImage
 subdir-		:= compressed
  
 setup-y		+= a20.o cmdline.o copy.o cpu.o cpucheck.o edd.o
  
  
@@ -71,17 +68,13 @@
 KBUILD_CFLAGS +=   $(call cc-option,-m32)
 KBUILD_AFLAGS	:= $(KBUILD_CFLAGS) -D__ASSEMBLY__
  
-$(obj)/zImage:  asflags-y := $(SVGA_MODE) $(RAMDISK)
-$(obj)/bzImage: ccflags-y := -D__BIG_KERNEL__
-$(obj)/bzImage: asflags-y := $(SVGA_MODE) $(RAMDISK) -D__BIG_KERNEL__
-$(obj)/bzImage: BUILDFLAGS   := -b
+$(obj)/bzImage: asflags-y  := $(SVGA_MODE)
  
 quiet_cmd_image = BUILD   $@
-cmd_image = $(obj)/tools/build $(BUILDFLAGS) $(obj)/setup.bin \
-	    $(obj)/vmlinux.bin $(ROOT_DEV) > $@
+cmd_image = $(obj)/tools/build $(obj)/setup.bin $(obj)/vmlinux.bin \
+	$(ROOT_DEV) > $@
  
-$(obj)/zImage $(obj)/bzImage: $(obj)/setup.bin \
-			      $(obj)/vmlinux.bin $(obj)/tools/build FORCE
+$(obj)/bzImage: $(obj)/setup.bin $(obj)/vmlinux.bin $(obj)/tools/build FORCE
 	$(call if_changed,image)
 	@echo 'Kernel: $@ is ready' ' (#'`cat .version`')'
  
@@ -24,12 +24,8 @@
 #include "boot.h"
 #include "offsets.h"
  
-SETUPSECTS	= 4			/* default nr of setup-sectors */
 BOOTSEG		= 0x07C0		/* original address of boot-sector */
-SYSSEG		= DEF_SYSSEG		/* system loaded at 0x10000 (65536) */
-SYSSIZE		= DEF_SYSSIZE		/* system size: # of 16-byte clicks */
-					/* to be loaded */
-ROOT_DEV	= 0			/* ROOT_DEV is now written by "build" */
+SYSSEG		= 0x1000		/* historical load address >> 4 */
  
 #ifndef SVGA_MODE
 #define SVGA_MODE ASK_VGA
  
  
@@ -97,12 +93,12 @@
 	.section ".header", "a"
 	.globl	hdr
 hdr:
-setup_sects:	.byte SETUPSECTS
+setup_sects:	.byte 0			/* Filled in by build.c */
 root_flags:	.word ROOT_RDONLY
-syssize:	.long SYSSIZE
-ram_size:	.word RAMDISK
+syssize:	.long 0			/* Filled in by build.c */
+ram_size:	.word 0			/* Obsolete */
 vid_mode:	.word SVGA_MODE
-root_dev:	.word ROOT_DEV
+root_dev:	.word 0			/* Filled in by build.c */
 boot_flag:	.word 0xAA55
  
 	# offset 512, entry point
  
@@ -123,14 +119,15 @@
 					# or else old loadlin-1.5 will fail)
 		.globl realmode_swtch
 realmode_swtch:	.word	0, 0		# default_switch, SETUPSEG
-start_sys_seg:	.word	SYSSEG
+start_sys_seg:	.word	SYSSEG		# obsolete and meaningless, but just
+					# in case something decided to "use" it
 		.word	kernel_version-512 # pointing to kernel version string
 					# above section of header is compatible
 					# with loadlin-1.5 (header v1.5). Don't
 					# change it.
  
-type_of_loader:	.byte	0		# = 0, old one (LILO, Loadlin,
-					#      Bootlin, SYSLX, bootsect...)
+type_of_loader:	.byte	0		# 0 means ancient bootloader, newer
+					# bootloaders know to change this.
 					# See Documentation/i386/boot.txt for
 					# assigned ids
  
  
@@ -142,11 +139,7 @@
 					# space behind setup.S can be used for
 					# heap purposes.
 					# Only the loader knows what is free
-#ifndef __BIG_KERNEL__
-		.byte	0
-#else
 		.byte	LOADED_HIGH
-#endif
  
 setup_move_size: .word  0x8000		# size to move, when setup is not
 					# loaded at 0x90000. We will move setup
  
@@ -157,11 +150,7 @@
  
 code32_start:				# here loaders can put a different
 					# start address for 32-bit code.
-#ifndef __BIG_KERNEL__
-		.long	0x1000		#   0x1000 = default for zImage
-#else
 		.long	0x100000	# 0x100000 = default for big kernel
-#endif
  
 ramdisk_image:	.long	0		# address of loaded ramdisk image
 					# Here the loader puts the 32-bit
@@ -33,47 +33,6 @@
 }
  
 /*
- * A zImage kernel is loaded at 0x10000 but wants to run at 0x1000.
- * A bzImage kernel is loaded and runs at 0x100000.
- */
-static void move_kernel_around(void)
-{
-	/* Note: rely on the compile-time option here rather than
-	   the LOADED_HIGH flag.  The Qemu kernel loader unconditionally
-	   sets the loadflags to zero. */
-#ifndef __BIG_KERNEL__
-	u16 dst_seg, src_seg;
-	u32 syssize;
-
-	dst_seg =  0x1000 >> 4;
-	src_seg = 0x10000 >> 4;
-	syssize = boot_params.hdr.syssize; /* Size in 16-byte paragraphs */
-
-	while (syssize) {
-		int paras  = (syssize >= 0x1000) ? 0x1000 : syssize;
-		int dwords = paras << 2;
-
-		asm volatile("pushw %%es ; "
-			     "pushw %%ds ; "
-			     "movw %1,%%es ; "
-			     "movw %2,%%ds ; "
-			     "xorw %%di,%%di ; "
-			     "xorw %%si,%%si ; "
-			     "rep;movsl ; "
-			     "popw %%ds ; "
-			     "popw %%es"
-			     : "+c" (dwords)
-			     : "r" (dst_seg), "r" (src_seg)
-			     : "esi", "edi");
-
-		syssize -= paras;
-		dst_seg += paras;
-		src_seg += paras;
-	}
-#endif
-}
-
-/*
  * Disable all interrupts at the legacy PIC.
  */
 static void mask_all_interrupts(void)
@@ -146,9 +105,6 @@
 {
 	/* Hook before leaving real mode, also disables interrupts */
 	realmode_switch_hook();
-
-	/* Move the kernel/setup to their final resting places */
-	move_kernel_around();
  
 	/* Enable the A20 gate */
 	if (enable_a20()) {
@@ -130,7 +130,7 @@
  
 static void usage(void)
 {
-	die("Usage: build [-b] setup system [rootdev] [> image]");
+	die("Usage: build setup system [rootdev] [> image]");
 }
  
 int main(int argc, char ** argv)
@@ -145,11 +145,6 @@
 	void *kernel;
 	u32 crc = 0xffffffffUL;
  
-	if (argc > 2 && !strcmp(argv[1], "-b"))
-	  {
-	    is_big_kernel = 1;
-	    argc--, argv++;
-	  }
 	if ((argc < 3) || (argc > 4))
 		usage();
 	if (argc > 3) {
@@ -216,8 +211,6 @@
 		die("Unable to mmap '%s': %m", argv[2]);
 	/* Number of 16-byte paragraphs, including space for a 4-byte CRC */
 	sys_size = (sz + 15 + 4) / 16;
-	if (!is_big_kernel && sys_size > DEF_SYSSIZE)
-		die("System is too big. Try using bzImage or modules.");
  
 	/* Patch the setup code with the appropriate size parameters */
 	buf[0x1f1] = setup_sectors-1;
 #ifndef _ASM_X86_BOOT_H
 #define _ASM_X86_BOOT_H
  
-/* Don't touch these, unless you really know what you're doing. */
-#define DEF_SYSSEG	0x1000
-#define DEF_SYSSIZE	0x7F00
-
 /* Internal svga startup constants */
 #define NORMAL_VGA	0xffff		/* 80x25 mode */
 #define EXTENDED_VGA	0xfffe		/* 80x50 mode */
...	...	@@ -6,26 +6,23 @@
6	6	# for more details.
7	7	#
8	8	# Copyright (C) 1994 by Linus Torvalds
	9	+# Changed by many, many contributors over the years.
9	10	#
10	11
11	12	# ROOT_DEV specifies the default root-device when making the image.
12	13	# This can be either FLOPPY, CURRENT, /dev/xxxx or empty, in which case
13	14	# the default of FLOPPY is used by 'build'.
14	15
15		-ROOT_DEV := CURRENT
	16	+ROOT_DEV := CURRENT
16	17
17	18	# If you want to preset the SVGA mode, uncomment the next line and
18	19	# set SVGA_MODE to whatever number you want.
19	20	# Set it to -DSVGA_MODE=NORMAL_VGA if you just want the EGA/VGA mode.
20	21	# The number is the same as you would ordinarily press at bootup.
21	22
22		-SVGA_MODE := -DSVGA_MODE=NORMAL_VGA
	23	+SVGA_MODE := -DSVGA_MODE=NORMAL_VGA
23	24
24		-# If you want the RAM disk device, define this to be the size in blocks.
25		-
26		-#RAMDISK := -DRAMDISK=512
27		-
28		-targets := vmlinux.bin setup.bin setup.elf zImage bzImage
	25	+targets := vmlinux.bin setup.bin setup.elf bzImage
29	26	subdir- := compressed
30	27
31	28	setup-y += a20.o cmdline.o copy.o cpu.o cpucheck.o edd.o
32	29
33	30
...	...	@@ -71,17 +68,13 @@
71	68	KBUILD_CFLAGS += $(call cc-option,-m32)
72	69	KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
73	70
74		-$(obj)/zImage: asflags-y := $(SVGA_MODE) $(RAMDISK)
75		-$(obj)/bzImage: ccflags-y := -D__BIG_KERNEL__
76		-$(obj)/bzImage: asflags-y := $(SVGA_MODE) $(RAMDISK) -D__BIG_KERNEL__
77		-$(obj)/bzImage: BUILDFLAGS := -b
	71	+$(obj)/bzImage: asflags-y := $(SVGA_MODE)
78	72
79	73	quiet_cmd_image = BUILD $@
80		-cmd_image = $(obj)/tools/build $(BUILDFLAGS) $(obj)/setup.bin \
81		- $(obj)/vmlinux.bin $(ROOT_DEV) > $@
	74	+cmd_image = $(obj)/tools/build $(obj)/setup.bin $(obj)/vmlinux.bin \
	75	+ $(ROOT_DEV) > $@
82	76
83		-$(obj)/zImage $(obj)/bzImage: $(obj)/setup.bin \
84		- $(obj)/vmlinux.bin $(obj)/tools/build FORCE
	77	+$(obj)/bzImage: $(obj)/setup.bin $(obj)/vmlinux.bin $(obj)/tools/build FORCE
85	78	$(call if_changed,image)
86	79	@echo 'Kernel: $@ is ready' ' (#'`cat .version`')'
87	80
...	...	@@ -24,12 +24,8 @@
24	24	#include "boot.h"
25	25	#include "offsets.h"
26	26
27		-SETUPSECTS = 4 /* default nr of setup-sectors */
28	27	BOOTSEG = 0x07C0 /* original address of boot-sector */
29		-SYSSEG = DEF_SYSSEG /* system loaded at 0x10000 (65536) */
30		-SYSSIZE = DEF_SYSSIZE /* system size: # of 16-byte clicks */
31		- /* to be loaded */
32		-ROOT_DEV = 0 /* ROOT_DEV is now written by "build" */
	28	+SYSSEG = 0x1000 /* historical load address >> 4 */
33	29
34	30	#ifndef SVGA_MODE
35	31	#define SVGA_MODE ASK_VGA
36	32
37	33
...	...	@@ -97,12 +93,12 @@
97	93	.section ".header", "a"
98	94	.globl hdr
99	95	hdr:
100		-setup_sects: .byte SETUPSECTS
	96	+setup_sects: .byte 0 /* Filled in by build.c */
101	97	root_flags: .word ROOT_RDONLY
102		-syssize: .long SYSSIZE
103		-ram_size: .word RAMDISK
	98	+syssize: .long 0 /* Filled in by build.c */
	99	+ram_size: .word 0 /* Obsolete */
104	100	vid_mode: .word SVGA_MODE
105		-root_dev: .word ROOT_DEV
	101	+root_dev: .word 0 /* Filled in by build.c */
106	102	boot_flag: .word 0xAA55
107	103
108	104	# offset 512, entry point
109	105
...	...	@@ -123,14 +119,15 @@
123	119	# or else old loadlin-1.5 will fail)
124	120	.globl realmode_swtch
125	121	realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
126		-start_sys_seg: .word SYSSEG
	122	+start_sys_seg: .word SYSSEG # obsolete and meaningless, but just
	123	+ # in case something decided to "use" it
127	124	.word kernel_version-512 # pointing to kernel version string
128	125	# above section of header is compatible
129	126	# with loadlin-1.5 (header v1.5). Don't
130	127	# change it.
131	128
132		-type_of_loader: .byte 0 # = 0, old one (LILO, Loadlin,
133		- # Bootlin, SYSLX, bootsect...)
	129	+type_of_loader: .byte 0 # 0 means ancient bootloader, newer
	130	+ # bootloaders know to change this.
134	131	# See Documentation/i386/boot.txt for
135	132	# assigned ids
136	133
137	134
...	...	@@ -142,11 +139,7 @@
142	139	# space behind setup.S can be used for
143	140	# heap purposes.
144	141	# Only the loader knows what is free
145		-#ifndef __BIG_KERNEL__
146		- .byte 0
147		-#else
148	142	.byte LOADED_HIGH
149		-#endif
150	143
151	144	setup_move_size: .word 0x8000 # size to move, when setup is not
152	145	# loaded at 0x90000. We will move setup
153	146
...	...	@@ -157,11 +150,7 @@
157	150
158	151	code32_start: # here loaders can put a different
159	152	# start address for 32-bit code.
160		-#ifndef __BIG_KERNEL__
161		- .long 0x1000 # 0x1000 = default for zImage
162		-#else
163	153	.long 0x100000 # 0x100000 = default for big kernel
164		-#endif
165	154
166	155	ramdisk_image: .long 0 # address of loaded ramdisk image
167	156	# Here the loader puts the 32-bit
...	...	@@ -33,47 +33,6 @@
33	33	}
34	34
35	35	/*
36		- * A zImage kernel is loaded at 0x10000 but wants to run at 0x1000.
37		- * A bzImage kernel is loaded and runs at 0x100000.
38		- */
39		-static void move_kernel_around(void)
40		-{
41		- /* Note: rely on the compile-time option here rather than
42		- the LOADED_HIGH flag. The Qemu kernel loader unconditionally
43		- sets the loadflags to zero. */
44		-#ifndef __BIG_KERNEL__
45		- u16 dst_seg, src_seg;
46		- u32 syssize;
47		-
48		- dst_seg = 0x1000 >> 4;
49		- src_seg = 0x10000 >> 4;
50		- syssize = boot_params.hdr.syssize; /* Size in 16-byte paragraphs */
51		-
52		- while (syssize) {
53		- int paras = (syssize >= 0x1000) ? 0x1000 : syssize;
54		- int dwords = paras << 2;
55		-
56		- asm volatile("pushw %%es ; "
57		- "pushw %%ds ; "
58		- "movw %1,%%es ; "
59		- "movw %2,%%ds ; "
60		- "xorw %%di,%%di ; "
61		- "xorw %%si,%%si ; "
62		- "rep;movsl ; "
63		- "popw %%ds ; "
64		- "popw %%es"
65		- : "+c" (dwords)
66		- : "r" (dst_seg), "r" (src_seg)
67		- : "esi", "edi");
68		-
69		- syssize -= paras;
70		- dst_seg += paras;
71		- src_seg += paras;
72		- }
73		-#endif
74		-}
75		-
76		-/*
77	36	* Disable all interrupts at the legacy PIC.
78	37	*/
79	38	static void mask_all_interrupts(void)
...	...	@@ -146,9 +105,6 @@
146	105	{
147	106	/* Hook before leaving real mode, also disables interrupts */
148	107	realmode_switch_hook();
149		-
150		- /* Move the kernel/setup to their final resting places */
151		- move_kernel_around();
152	108
153	109	/* Enable the A20 gate */
154	110	if (enable_a20()) {
...	...	@@ -130,7 +130,7 @@
130	130
131	131	static void usage(void)
132	132	{
133		- die("Usage: build [-b] setup system [rootdev] [> image]");
	133	+ die("Usage: build setup system [rootdev] [> image]");
134	134	}
135	135
136	136	int main(int argc, char ** argv)
...	...	@@ -145,11 +145,6 @@
145	145	void *kernel;
146	146	u32 crc = 0xffffffffUL;
147	147
148		- if (argc > 2 && !strcmp(argv[1], "-b"))
149		- {
150		- is_big_kernel = 1;
151		- argc--, argv++;
152		- }
153	148	if ((argc < 3) \|\| (argc > 4))
154	149	usage();
155	150	if (argc > 3) {
...	...	@@ -216,8 +211,6 @@
216	211	die("Unable to mmap '%s': %m", argv[2]);
217	212	/* Number of 16-byte paragraphs, including space for a 4-byte CRC */
218	213	sys_size = (sz + 15 + 4) / 16;
219		- if (!is_big_kernel && sys_size > DEF_SYSSIZE)
220		- die("System is too big. Try using bzImage or modules.");
221	214
222	215	/* Patch the setup code with the appropriate size parameters */
223	216	buf[0x1f1] = setup_sectors-1;
1	1	#ifndef _ASM_X86_BOOT_H
2	2	#define _ASM_X86_BOOT_H
3	3
4		-/* Don't touch these, unless you really know what you're doing. */
5		-#define DEF_SYSSEG 0x1000
6		-#define DEF_SYSSIZE 0x7F00
7		-
8	4	/* Internal svga startup constants */
9	5	#define NORMAL_VGA 0xffff /* 80x25 mode */
10	6	#define EXTENDED_VGA 0xfffe /* 80x50 mode */