[SRU][focal/linux-riscv-5.8][PATCH 0/1] gcc version used for kernel configs doesn't match the one used for builds

[Kleber Sacilotto de Souza]

BugLink: https://bugs.launchpad.net/bugs/1933856

[Impact]
linux-riscv-5.8 needs to be built with gcc-10 in Focal otherwise it won't boot.
This was fixed by commit "UBUNTU: [Packaging] Use gcc-10 for riscv 5.8 kernel
build", which adds gcc-10 as "Build-Depends-Arch" and sets a variable "gcc" in
'debian/rules', which is passed down to make by
'debian/rules.d/2-binary-arch.mk'.

The other gcc version dependency is when we generate locally the kernel configs
by running 'make syncconfig', which is called by
'debian/scripts/misc/kernelconfig'. Currently, the syncconfig is called using
the chroot default compiler, which in Focal is gcc-9. So far there hasn't been
any major differences, however with the update of gcc-10 in Groovy and Focal
from 10.2.0 to 10.3.0 some KASAN related config options are not available
anymore, causing some changes on the configs generated. The problem with
non-matching gcc versions being used, is that there will be a mismatch between
the configs being generated during the preparation of the kernel and the ones
during the build.

[Fix]
The proposed fix is to use the same variable defined for the build, passing it
down to 'debian/scripts/misc/kernelconfig' and using it to define the correct
cross-compiler to be used.

[Where problems could occur]
If the environment variables are not set correctly the build can break in some
environment which was not tested.

Kleber Sacilotto de Souza (1):
  UBUNTU: [Packaging] Use gcc-10 for riscv-5.8 kernel configs

 debian/rules.d/1-maintainer.mk   | 4 ++--
 debian/scripts/misc/kernelconfig | 7 ++++---
 2 files changed, 6 insertions(+), 5 deletions(-)

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2.27.0