src/driver/linux_resource/kernel_compat.sh fails when ARCH is set to a bogus value in the environment

[ajschorr]

Hi,

I happened to attempt to compile with a non-standard value of ARCH set in my environment,
and the build crapped out with this error:

kernel_compat.sh: Kernel build tree is unable to build modules

Here's a reproducer:

sh-5.1$ unset ARCH
sh-5.1$ ./src/driver/linux_resource/kernel_compat.sh -k /usr/src/kernels/5.14.0-115.el9.x86_64 -q > /dev/null && echo GOOD
GOOD
sh-5.1$ ARCH=fubar ./src/driver/linux_resource/kernel_compat.sh -k /usr/src/kernels/5.14.0-115.el9.x86_64 -q > /dev/null && echo GOOD
kernel_compat.sh: Kernel build tree is unable to build modules

Is this a bug or a feature? It seems at the very least a bit confusing that builds are vulnerable
to failing like this. Is this documented somewhere?

Regards,
Andy