Re: [PATCH] x86: Start removing X86_X32_ABI

[David Laight]

On Tue, 26 May 2026 08:54:56 -0700
"H. Peter Anvin" <hpa@xxxxxxxxx> wrote:

> On May 26, 2026 3:40:51 AM PDT, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote:
> >On 2026-05-23 14:43:52 [-0700], H. Peter Anvin wrote:  
> >> However, we can not recycle the syscall numbers. The x32 flag in the
> >> syscall number was advisory originally; it was introduced late in the
> >> game to work around a design bug in the input subsystem (*).  
> >
> >If x32 is removed/ not supported why can't the 32/64 bit ABI use syscall
> >numbers 512+? It is an ELF32 with EM_X86_64 which should be rejected.
> >Shouldn't this free the space because there are no users anymore?
> >  
> >>    -hpa  
> >
> >Sebastian  
> 
> System call numbers or even mechanisms are in no wise tied to the ELF type.
> An x86-64 binary can issue x86-64, x32 or i386 system calls, even from 64-bit mode! 
> 

I suspect a 32bit binary can also switch to 64bit mode and issue any
of them as well.

-- David