APPLIED: [PATCH 0/6][Unstable] Kernel package builds running out of space on builders

[Seth Forshee]

On Thu, Jun 03, 2021 at 09:47:13PM -0500, Seth Forshee wrote:
> BugLink: https://bugs.launchpad.net/bugs/1930713
> 
> [Impact]
> 
> Our kernel builds are sometimes running out of space on the builders when we
> are building multiple flavours. We've seen this with focal:linux-hwe for amd64
> and impish:linux-unstable for arm64. This is in part because package builds are
> broken up into a build phase (which builds the source tree) and a binary phase
> (which creates the debs). These are run separately, with the binary phase run
> under fakeroot to get correct ownership for files in the package archives,
> requiring builds for multiple flavours to be present on disk at the same time.
> 
> We have implemented various fixes for this problem over time, and explored many
> others which have not worked out. But the size of the kernel keeps increasing,
> and now it seems our only remaining option is to build one flavour and install
> its files, then remove the flavour build files before building the next
> flavour. This means that files are installed for later package builds during
> the build phase, requiring that ownership of these files be fixed up during the
> binary phase to get correct ownership in the package archives.
> 
> [Test Plan]
> 
> Build a full set of kernel packages (inlcuding linux-source and dbgsym
> packages, which are generally excluded when not building on builders) at a
> given tag, then build another set from the same tag with the packaging changes
> applied. Compare the resulting debs to confirm that the set of produced
> packages is the same, the file lists within the packages are the same, and that
> file ownership and permissions between the packages is identical.
> 
> I have done this testing with the proposed patches with a recent linux-unstable
> tag and found no differences with and without the changes.
> 
> [Where problems could occur]
> 
> Incorrect ownership of files in the package archives is the main concern. I
> have tested for this, but it is possible that future upstream changes could
> unexpectedly result in files with incorrect ownership.
> 
> Reordering of the package build sequence could result in missing files which
> should be in packages, or files present in packages which should be excluded.
> Some instances of this occurred while developing these changes and have been
> fixed. Future updates to upstream or to the packaging could cause additional
> issues.
> 
> Changes since v1:
>  - Test paths to decide whether to fix ownership for a package instead of
>    using build variables.

Applied patches 1-5 to unstable/master.