Re: [PATCH] x86: Start removing X86_X32_ABI

[Arnd Bergmann]

On Sat, May 23, 2026, at 11:37, Sebastian Andrzej Siewior wrote:
>
> The last syscall for x86_64 is currently at 471. The first x32 starts at
> 512 which leaves 40 new syscalls in between. Without the x32 ABI, those
> syscalls could be used since x32 wouldn't be an option and therefore
> reserved.
>
> Since there is practically no real use for x32, start removing it by
> removing the symbol first, not allowing to enable it. Should nothing
> happening within the next half year, lets remove code bits around August
> after the summer break.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

I think the main reason to remove x32 support is all the special
cases we have for it where it is different from normal 'compat'
syscall and ioctl handling, which leaks all the way into file
systems and device drivers (sound/core/pcm_compat.c,
fs/fuse/ioctl.c, fs/read_write, ...) as well as user space
trying to handle 64-bit time_t in a portable way.

I agree removing the Kconfig symbol (or marking it as 'depends
on BROKEN' as we did for arm64 big-endian mode) is a good
idea at this time, but I think the timing for removing the
actual implementation should allow the next LTS kernel (7.4?)
to be released with the current level of support still present.

        Arnd