[bitbake-devel] [PATCH v2 1/2] gitsm.py: use download cache for git submodules too

[Christopher Larson]

On Wed, Sep 6, 2017 at 5:33 AM, Mikko Rapeli <mikko.rapeli at bmw.de> wrote:

> Currently download caches for recipes using gitsm are filled also with
> the submodule repositories but when the git submodule tree is reused from
> cache, only the base repository is cloned. After a source URL rewrite,
> 'git submodule update --init --recursive' is called in the tree
> which downloads the needed submodules from upstream URL's.
> This wastes bandwidth since download cache already had the needed
> commits for the submodule repositories.
>
> With this change, also the submodule repositories are copied to the
> work space from download cache and the download from upstream can
> be avoided. Using plain 'cp -a' since git cloning doesn't work for the
> submodule directories.
>

This behavior is both already tracked by a yocto bug, and blindly copying
will result in breakage when the branch changes in such a way that the
submodules change. I already submitted an equivalent patch a week or two
ago and then decided against its inclusion, as it just runs into other
failures, specifically there was an oe-selftest that fails if you had
previously fetched a different branch of the sources in question, as the
upstream url of one of the submodules changes between branches, and we
don’t re-fetch existing submodules when their urls change. We definitely
need to fix this, but this fixes one problem and introduces others.

See https://bugzilla.yoctoproject.org/show_bug.cgi?id=11830 and
https://bugzilla.yoctoproject.org/show_bug.cgi?id=11831 for reference.
-- 
Christopher Larson
kergoth at gmail dot com
Founder - BitBake, OpenEmbedded, OpenZaurus
Senior Software Engineer, Mentor Graphics
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