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+.. SPDX-License-Identifier: GPL-2.0+
+
+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
+
+Alignment issues
+----------------
+
+The linker script uses alphabetic sorting to group the different linker
+lists together. Each group has its own struct and potentially its own
+alignment. But when the linker packs the structs together it cannot ensure
+that a linker list starts on the expected alignment boundary.
+
+For example, if the first list has a struct size of 8 and we place 3 of
+them in the image, that means that the next struct will start at offset
+0x18 from the start of the linker_list section. If the next struct has
+a size of 16 then it will start at an 8-byte aligned offset, but not a
+16-byte aligned offset.
+
+With sandbox on x86_64, a reference to a linker list item using
+ll_entry_get() can force alignment of that particular linker_list item,
+if it is in the same file as the linker_list item is declared.
+
+Consider this example, where struct driver is 0x80 bytes::
+
+    ll_entry_declare(struct driver, fred, driver)
+
+    ...
+
+    void *p = ll_entry_get(struct driver, fred, driver)
+
+If these two lines of code are in the same file, then the entry is forced
+to be aligned at the 'struct driver' alignment, which is 16 bytes. If the
+second line of code is in a different file, then no action is taken, since
+the compiler cannot update the alignment of the linker_list item.
+
+In the first case, an 8-byte 'fill' region is added::
+
+   .u_boot_list_2_driver_2_testbus_drv
+               0x0000000000270018       0x80 test/built-in.o
+               0x0000000000270018                _u_boot_list_2_driver_2_testbus_drv
+   .u_boot_list_2_driver_2_testfdt1_drv
+               0x0000000000270098       0x80 test/built-in.o
+               0x0000000000270098                _u_boot_list_2_driver_2_testfdt1_drv
+   *fill*         0x0000000000270118        0x8
+   .u_boot_list_2_driver_2_testfdt_drv
+               0x0000000000270120       0x80 test/built-in.o
+               0x0000000000270120                _u_boot_list_2_driver_2_testfdt_drv
+   .u_boot_list_2_driver_2_testprobe_drv
+               0x00000000002701a0       0x80 test/built-in.o
+               0x00000000002701a0                _u_boot_list_2_driver_2_testprobe_drv
+
+With this, the linker_list no-longer works since items after testfdt1_drv
+are not at the expected address.
+
+Ideally we would have a way to tell gcc not to align structs in this way.
+It is not clear how we could do this, and in any case it would require us
+to adjust every struct used by the linker_list feature.
+
+The simplest fix seems to be to force each separate linker_list to start
+on the largest possible boundary that can be required by the compiler. This
+is the purpose of CONFIG_LINKER_LIST_ALIGN
+
+
+.. kernel-doc:: include/linker_lists.h
+   :internal: