Linker-Generated Arrays

A linker list is constructed by grouping together linker input sections, each containing one entry of the list. Each input section contains a constant initialized variable which holds the entry's content. Linker list input sections are constructed from the list and entry names, plus a prefix which allows grouping all lists together. Assuming _list and _entry are the list and entry names, then the corresponding input section name is

.u_boot_list_ + 2_ + @_list + _2_ + @_entry

and the C variable name is

_u_boot_list + _2_ + @_list + _2_ + @_entry

This ensures uniqueness for both input section and C variable name.

Note that the names differ only in the first character, "." for the section and "_" for the variable, so that the linker cannot confuse section and symbol names. From now on, both names will be referred to as

%u_boot_list_ + 2_ + @_list + _2_ + @_entry

Entry variables need never be referred to directly.

The naming scheme for input sections allows grouping all linker lists into a single linker output section and grouping all entries for a single list.

Note the two '_2_' constant components in the names: their presence allows putting a start and end symbols around a list, by mapping these symbols to sections names with components "1" (before) and "3" (after) instead of "2" (within). Start and end symbols for a list can generally be defined as

%u_boot_list_2_ + @_list + _1_...
%u_boot_list_2_ + @_list + _3_...

Start and end symbols for the whole of the linker lists area can be defined as

%u_boot_list_1_...
%u_boot_list_3_...

Here is an example of the sorted sections which result from a list "array" made up of three entries : "first", "second" and "third", iterated at least once.

.u_boot_list_2_array_1
.u_boot_list_2_array_2_first
.u_boot_list_2_array_2_second
.u_boot_list_2_array_2_third
.u_boot_list_2_array_3

If lists must be divided into sublists (e.g. for iterating only on part of a list), one can simply give the list a name of the form 'outer_2_inner', where 'outer' is the global list name and 'inner' is the sub-list name. Iterators for the whole list should use the global list name ("outer"); iterators for only a sub-list should use the full sub-list name ("outer_2_inner").

Here is an example of the sections generated from a global list named "drivers", two sub-lists named "i2c" and "pci", and iterators defined for the whole list and each sub-list:

%u_boot_list_2_drivers_1
%u_boot_list_2_drivers_2_i2c_1
%u_boot_list_2_drivers_2_i2c_2_first
%u_boot_list_2_drivers_2_i2c_2_first
%u_boot_list_2_drivers_2_i2c_2_second
%u_boot_list_2_drivers_2_i2c_2_third
%u_boot_list_2_drivers_2_i2c_3
%u_boot_list_2_drivers_2_pci_1
%u_boot_list_2_drivers_2_pci_2_first
%u_boot_list_2_drivers_2_pci_2_second
%u_boot_list_2_drivers_2_pci_2_third
%u_boot_list_2_drivers_2_pci_3
%u_boot_list_2_drivers_3