Re: custom-kernel headers: scripts are wrong architecture

["Koch, Stefan" <stefan-koch@siemens.com>]

@Jan:
This is fixed by the patch "linux-module: Support emulated module build
with cross-compiled kernel"

On Wed, 2024-01-17 at 20:37 +0000, Moessbauer, Felix (T CED OES-DE)
wrote:
> Dear devs,
>
> while debugging a broken non-cross kernel module build, I found that
> there is a more generic issue about our linux-headers-${KERNEL_NAME}
> package: It might contain the kernel scripts (ELF binaries) in the
> wrong architecture. This only happens if the kernel itself is cross-
> compiled.
>
> Let's consider the following example, where we compile for a debian
> bookworm arm64 target. We further look at the 'fixdeps' script from
> the
> kernel tools (required during kmod builds).
>
> Example 1 (stock kernel):
>
> The script is located in package linux-kbuild-6.1 (dependency of
> linux-
> headers-<...>).
> - file /usr/lib/linux-kbuild-6.1/scripts/basic/fixdep: ELF 64-bit LSB
> pie executable, ARM aarch64, ...
> - linux-headers-arm64 : arm64
> - linux-kbuild-6.1 : arm64
>
> Example 2 (custom kernel):
>
> - file /usr/src/linux-headers-6.1.54-cip6-rt3/scripts/basic/fixdep:
> ELF
> 64-bit LSB pie executable, x86-64
> - linux-headers-iot2050-rt : arm64
>
> In example 2, the kmod build is obviously broken, as the emulated
> build
> will not be able to execute the x64 binary. Also, in an :arm64
> package,
> there must be no foreign architecture binaries.
>
> This behavior can also be reproduced, by cross-compiling a target
> with
> a custom kernel and disabling the cross-build for a module, using
> ISAR_CROSS_COMPILE="0" in the module build recipe.
>
> It would be great, if someone could have a look there. At a first
> glance, this issue looks closely related to "linux-custom: Split up
> binaries from kernel headers to kbuild packages". Maybe Stefan can
> comment on this as well.
>
> PS: This bug was uncovered today, as the cross-build of a kernel
> module
> on debian bookworm arm64 is currently broken in upstream debian. I
> already reported this bug in [1].
>
> [1]
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1061075
>
> Best regards,
> Felix
>

--
Stefan Koch
Siemens AG
http://www.siemens.com/