Buildroot patches not applied for overriden package?

Question

I'm playing around with patches in Buildroot (version 2017.02), but when I override the package sources in local.mk:

PACKAGENAME_OVERRIDE_SRCDIR = /...path_to_local_checkout

I see that the Buildroot patches are not applied for this package.

They are applied only if the package is not overriden in local.mk.

Is this expected behavior?

---

Notes:

• I didn't find the answer to my question in the Buildroot manual: https://buildroot.org/downloads/manual/manual.html#patch-apply-order
• The package I'm testing is the Linux kernel, but I guess it's unrelated.
• I put my patches in the global patch dir board/company_name/common/patches/...

Answer 1

Yes, this is expected behavior. If you use <pkg>_OVERRIDE_SRCDIR, then the source tree for the package is available locally, so you should apply the patches to your source tree. Buildroot cannot know which version of the package you're using, and therefore the patches it has in package/<pkg> may not apply, which is why the behavior is as you've seen that patches are not applied to overridden packages.

Essentially, the flow for a regular package is: download -> extract -> patch -> configure -> build -> install.

The flow for an overridden package is: rsync -> configure -> build -> install.

Answer 2

This behavior is documented in the current version of the documentation:

When Buildroot finds that for a given package, an <pkg>_OVERRIDE_SRCDIR has been defined, it will no longer attempt to download, extract and patch the package. Instead, it will directly use the source code available in the specified directory and make clean will not touch this directory. This allows to point Buildroot to your own directories, that can be managed by Git, Subversion, or any other version control system. To achieve this, Buildroot will use rsync to copy the source code of the component from the specified <pkg>_OVERRIDE_SRCDIR to output/build/-custom/.

I would just go and apply all the Buildroot patches to the package and keep them git tracked.

Most of them (TODO all?) seem to be cherry picked from future versions on master, so I would just cherry pick them as much as possible.

It would be beautiful if Buildroot itself could use git submodules for every package and keep it under their fork: github.com/buildroot/ but there are likely technical limitations to this such as Git shallow cloning annoyances.