1  # Managing local additions
 2  
 3  This section describes the site-local mechanism, what it is good for and
 4  how it can be used.
 5  
 6  ## What is site-local?
 7  site-local is the name of a directory that won't ever appear in the
 8  upstream coreboot repository but is referred to in several key places of its
 9  configuration and build system. The intent is provide a single location to
10  store local modifications.
11  
12  By keeping local additions to builds in this place, it can be versioned
13  independently from upstream (e.g. controlled by git in another repository)
14  and any changes made there won't ever conflict with upstream changes.
15  
16  This optional directory is searched for in the top-level of the coreboot
17  repo and is called `site-local`.
18  
19  A common approach for developing and testing internal additions to coreboot
20  from the site-local directory is to use `symlink` targets. By replicating
21  the coreboot directory structure within site-local and creating a
22  `symlink.txt` file that contains the path (relative to the root of the
23  coreboot directory), the `symlink` target can recursively scan the
24  site-local directory and create symbolic links into the coreboot tree,
25  allowing the build process to proceed as if the additions were integrated
26  directly into the main coreboot tree. The `symlink.txt` file must be placed
27  at the root of the new directory.
28  
29  The following targets can be used to create/remove the symlinks:
30  
31  `make symlink` - Creates symbolic links from site-local into coreboot tree
32  `make clean-symlink` - Removes symbolic links created by `make symlink`
33  `make cleanall-symlink` - Removes all symbolic links in the coreboot tree
34  
35  ### Example symlink usage
36  Directory structure with symlink from site-local into coreboot:
37  
38  ```
39  coreboot/
40  ├── src/
41  │   └── soc/
42  │       ├── amd/
43  │       ├── cavium/
44  │       ├── example/
45  │       ├── ...
46  │       └── test-soc-from-site-local -> ../../site-local/src/soc/test-soc-from-site-local/
47  └── site-local/
48      ├── Kconfig
49      ├── Makefile.mk
50      └── src/
51          └── soc/
52              └── test-soc-from-site-local/
53                  └── symlink.txt
54  ```
55  
56  Contents of `symlink.txt`:
57  
58  ```
59  src/soc/test-soc-from-site-local
60  ```
61  
62  *Note:* To keep the symlinks updated throughout development, the following
63  line may be added to `site-local/Makefile.mk` to declare symlink as a
64  `site-local-target` dependency, ensuring the symlink target is run anytime
65  `make` is executed:
66  ```
67  site-local-target:: symlink
68  ```
69  
70  ## Integration into the configuration system
71  Kconfig includes `site-local/Kconfig` relatively early, so it can be used
72  to pre-define some configuration before coreboot's regular ruleset sets
73  up defaults.
74  
75  ## Integration into the build system
76  The build system includes, if present, `site-local/Makefile.mk`. The main
77  purpose so far has been to add additional files to a CBFS image. A single
78  Makefile.inc can serve multiple boards, for example:
79  
80      cbfs-files-$(CONFIG_BOARD_INTEL_D945GCLF) += pci8086,2772.rom
81      pci8086,2772.rom-file := intel_d945gclf/pci8086,2772.rom
82      pci8086,2772.rom-type := optionrom
83  
84      cbfs-files-$(CONFIG_BOARD_KONTRON_986LCD_M) += pci8086,27a2.rom
85      pci8086,27a2.rom-file := kontron_986lcd-m/pci8086,27a2.rom
86      pci8086,27a2.rom-type := optionrom
87  
88  This adds the correct Option ROM binary (which are non-redistributable and
89  therefore can't become part of the coreboot.org repos) to coreboot.rom when
90  built for intel/d945gclf or kontron/986lcd-m.