Re: [PATCH v4 2/2] x86: Start removing X86_X32_ABI

[Tancred]

On 10/8/26 03:07, Sebastian Andrzej Siewior wrote:
> where certain workloads widely
> move to x32 and use it exclusively. In the meantime Debian introduced a
> patch to disable x32 by default (so it has to be enabled at boot time on
> the command line) because they are afraid of the increased attack
> surface. Fedora as far as I tell has X32 disabled (looking at 7.0-rc5
> rpm in rawhide).
>
> Since there is practically no real use for x32

I only recently discovered x32 and built a Desktop (with all daemons and 
utilities running 10-30% smaller and some a bit faster, with 64 bit 
libraries for eg. Firefox.) My experiment should definitely not decide 
anything, but how much real-world use would be sufficient to justify 
continued presence (more complex compat code)?

If left behind a flag like Debian (like the 2014 proposal 
https://lore.kernel.org/lkml/1415245982.3398.53.camel@xxxxxxxxxxxxxxx/), 
there are no security risks so I understand the benefit is reduced code 
complexity and maintenance burden. Older threads critiqued the 
implementation. What's the smallest kernel support which would keep 
32-bit pointers possible? Could a small design (eg. just 32-bit pointers 
on x86-64 with i386's type layout, so no 3rd compat case (cf. MIPS n32 
and o32)) work?

- Alex Alejandre