RE: sstate can result in inconsistent kernel and modules

["MOESSBAUER, FELIX JONATHAN" <felix.moessbauer@siemens.com>]

> -----Original Message-----
> From: Kiszka, Jan (T CED) <jan.kiszka@siemens.com>
> Sent: Monday, October 17, 2022 2:00 PM
> To: Moessbauer, Felix Jonathan (T CED INW-CN)
> <felix.moessbauer@siemens.com>; isar-users@googlegroups.com; Schmidt,
> Adriaan (T CED SES-DE) <adriaan.schmidt@siemens.com>
> Cc: Schild, Henning (T CED SES-DE) <henning.schild@siemens.com>
> Subject: Re: sstate can result in inconsistent kernel and modules
> 
> On 16.10.22 07:48, Moessbauer, Felix Jonathan (T CED INW-CN) wrote:
> > Dear ISAR users,
> >
> > I just discovered the following bug on a re-build using the sstate cache:
> >
> > The installed kernel version in the image is 5.19.6-1, while the kernel
> modules are built for 5.19.0-2.
> > The reason is that the modules are extracted from the sstate cache, but
> bitbake does not know about the "exact" kernel revision used for building.
> >
> > Actually, I don't know how to easily solve that issue, as bitbake does not
> know about the exact Debian package versions.
> > But what could be done is to check for version incompatibilities in the final
> rootfs.
> > Or we disable the sstate cache for module builds (but I don't know how to
> do that).
> 
> How was this inconsistency created? Did you select a different kernel version
> from the same isar-bootstrap generated apt database? Because if the latter
> changes, all recipes and cached artifacts downstream should change as well.

This happened on a Debian bookworm build where kernel updates happen quite often.
The custom modules have been extracted from the cache, but the target rootfs got a more recent kernel.
By that, the modules (built for 5.19.0-2) where installed in an image with kernel 5.19.6-1, hence could not be loaded.

I don't know if there is an apt upgrade running right after assembling the rootfs, or if simply the target rootfs could not be extracted from the cache.

Maybe, the module recipe should add a runtime depends on the exact version of the kernel used for building.
This would at least break the build, instead of failing silently.

Felix

> 
> Jan
> 
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> Siemens AG, Technology
> Competence Center Embedded Linux