Re: [PATCH] x86: Start removing X86_X32_ABI

[Sebastian Andrzej Siewior]

On 2026-05-28 09:05:48 [+0200], Tomas Glozar wrote:
> FWIW, T2 Linux [1] also has an option to build x32, and there have been such
> builds last year [2]. Since this year, it switched to building KDE Plasma
> desktop ISOs, where x32 makes less sense, though, as modern desktop is rather
> RAM-hungry.

I wasn't aware of this. If an application, such as chromium, is memory
hungry the x32 doesn't help much to contain it. Your pointer are
smaller, granted, but the overall memory consumption is still
significant. Running x32 means also that a single application is not
able to use more than 4GiB or memory.

> [1] https://t2linux.com
> [2] https://dl.t2sde.org/binary/2025/t2-25.10-x32-base-wayland-glibc-gcc-nocona.iso
> 
> Also at least 6 years ago, x32 was reported there to increase performance by
> some 5-8% [3] likely thanks to smaller pointers allowing better cache
> utilization. That is not insignificant, and not all tasks require gigabytes of
> RAM (e.g. compression and encryption, as shown in the link).

Arnd told me quite some time ago that cross compiling (or compiling in
general) has better performance on x32 than x86-64. This was the only
case afaik. 

> [3] https://www.youtube.com/live/Mw-ravkg67k?si=HS7ZHZyg_FKXPZUz&t=387 (yeah
> YouTube video not the best source...)

So from that linked video, there few cases where x32 builds quicker. But
then at 9.51 there is runtime x64-O2 is leading. The video is titled
5%-8% but I don't see where this is from.

> Tomas

Sebastian