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

[Willy Tarreau <w@1wt.eu>]

On Sun, Oct 11, 2026 at 07:19:46PM +0200, Sebastian Andrzej Siewior wrote:
> On 2026-10-09 20:13:55 [-0600], Tancred wrote:
> > 
> > 
> > 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)?
> 
> "a bit faster" needs actual numbers to justify. One examples was quicker
> gcc but I don't see a x32 compile farm leveraging this benefit.

FWIW I do build my ARM cross-compilers in a32 because they're generally
~10-15% faster than in a64. I wouldn't be surprised if that was the same
on x86 because tools such as compilers very likely use pointers a lot. In
a build farm it certainly makes a difference, possibly not sufficient to
justify keeping a kernel port, but it's just to illustrate one valid use
case.

Willy