coreboot-kgpe-d16/Documentation/tutorial/managing_local_additions.md

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Managing local additions

This section describes the site-local mechanism, what it is good for and how it can be used.

What is site-local?

site-local is the name of a directory that won't ever appear in the upstream coreboot repository but is referred to in several key places of its configuration and build system. The intent is provide a single location to store local modifications.

By keeping local additions to builds in this place, it can be versioned independently from upstream (e.g. controlled by git in another repository) and any changes made there won't ever conflict with upstream changes.

This optional directory is searched for in the top-level of the coreboot repo and is called site-local.

Integration into the configuration system

Kconfig includes site-local/Kconfig relatively early, so it can be used to pre-define some configuration before coreboot's regular ruleset sets up defaults.

Integration into the build system

The build system includes, if present, site-local/Makefile.inc. The main purpose so far has been to add additional files to a CBFS image. A single Makefile.inc can serve multiple boards, for example:

cbfs-files-$(CONFIG_BOARD_INTEL_D945GCLF) += pci8086,2772.rom
pci8086,2772.rom-file := intel_d945gclf/pci8086,2772.rom
pci8086,2772.rom-type := optionrom

cbfs-files-$(CONFIG_BOARD_KONTRON_986LCD_M) += pci8086,27a2.rom
pci8086,27a2.rom-file := kontron_986lcd-m/pci8086,27a2.rom
pci8086,27a2.rom-type := optionrom

This adds the correct Option ROM binary (which are non-redistributable and therefore can't become part of the coreboot.org repos) to coreboot.rom when built for intel/d945gclf or kontron/986lcd-m.