linux: aarch64: dont build with CONFIG_COMPAT

[heitbaum]

Unset the option provided for enabling support for a 32-bit EL0 running under a 64-bit kernel at EL1. AArch32-specific components such as system calls, the user helper functions, VFP support and the ptrace interface are handled appropriately by the kernel.

[HiassofT]

I'm not sure we will want that, as this will remove the possibility to run 32bit programs (statically linked binaries, containers etc) which can be helpful at times.

Here's the more understandable second part of the kconfig help:

If you use a page size other than 4KB (i.e, 16KB or 64KB), please be aware
that you will only be able to execute AArch32 binaries that were compiled
with page size aligned segments.

If you want to execute 32-bit userspace applications, say Y.

RPi5 might be debatable because of it's 16k page size (so usual 32bit programs compiled for 4k page size won't run) but on the other systems I'd rather keep this config as it is now.

[heitbaum]

I'm not sure we will want that, as this will remove the possibility to run 32bit programs (statically linked binaries, containers etc) which can be helpful at times.

Here's the more understandable second part of the kconfig help:

If you use a page size other than 4KB (i.e, 16KB or 64KB), please be aware
that you will only be able to execute AArch32 binaries that were compiled
with page size aligned segments.
If you want to execute 32-bit userspace applications, say Y.

RPi5 might be debatable because of it's 16k page size (so usual 32bit programs compiled for 4k page size won't run) but on the other systems I'd rather keep this config as it is now.

I’m fine dropping the PR, more that we had moved to 64bit thus LE would not need to run 32bit binaries.

(You are correct - it would limit aarch64 from running static 32bit binaries. Question is “are there any 32 bit static binaries that should/need to be run on LE aarch64?” That is probably where I don’t know the answer.)