In smaller projects and organizations, forking Zephyr is usually
a tenable solution for development continuity, in the case that
bug-fixes or enhancements need to be applied to Zephyr to
unblock development.
In larger organizations, perhaps in the absence of healthy patch
management, technical debt management, and open-source policies,
forking and in-tree changes can quickly get out of hand.
In other organizations, it may simply be preferable to have a
zero-forking / upstream-first policy.
Regardless of the reason, this change adds a `west patch`
command that enables users to manage patches locally in their
modules, under version control, with complete transparence.
The format of the YAML file (detailed in a previous comit)
includes fields for filename, checksum, author, email, dates,
along with pr and issue links. There are fields indicating
whether the patch is upstreamble or whether it has been merged
upstream already. There is a custom field that is not validated
and can be used for any purpose.
Workflows can be created to notify maintainers when a merged
patch may be discarded after a version or a commit bump.
In Zephyr modules, the file resides conventionally under
`zephyr/patches.yml`, and patch files reside under
`zephyr/patches/`.
Sample usage applying patches (the `-v` argument for additional
detail):
```shell
west -v patch apply
reading patch file zephyr/run-tests-with-rtt-console.patch
checking patch integrity... OK
patching zephyr... OK
reading patch file zephyr/twister-rtt-support.patch
checking patch integrity... OK
patching zephyr... OK
reading patch file zephyr/multiple_icntl.patch
checking patch integrity... OK
patching zephyr... OK
reading patch file zephyr/move-bss-to-end.patch
checking patch integrity... OK
patching zephyr... OK
4 patches applied successfully \o/
```
Cleaning previously applied patches
```shell
west patch clean
```
After manually corrupting a patch file (the `-r` option will
automatically roll-back all changes if one patch fails)
```shell
west -v patch apply -r
reading patch file zephyr/run-tests-with-rtt-console.patch
checking patch integrity... OK
patching zephyr... OK
reading patch file zephyr/twister-rtt-support.patch
checking patch integrity... OK
patching zephyr... OK
reading patch file zephyr/multiple_icntl.patch
checking patch integrity... OK
patching zephyr... OK
reading patch file zephyr/move-bss-to-end.patch
checking patch integrity... FAIL
ERROR: sha256 mismatch for zephyr/move-bss-to-end.patch:
expect: 00e42e5d89f68f8b07e355821cfcf492faa2f96b506bbe87a9b35a823fd719cb
actual: b9900e0c9472a0aaae975370b478bb26945c068497fa63ff409b21d677e5b89f
Cleaning zephyr
FATAL ERROR: failed to apply patch zephyr/move-bss-to-end.patch
```
Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>
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