Re: [PATCH v2] x86: Start removing X86_X32_ABI

[David Laight]

On Wed, 8 Jul 2026 17:27:46 +0100 (BST)
"Maciej W. Rozycki" <macro@xxxxxxxxxxx> wrote:

> On Wed, 8 Jul 2026, Arnd Bergmann wrote:
> 
> > As I understand, it's a policy in Debian for debian-installer and
> > the kernel packages to only provide kernels for the native
> > architecture, i.e. 64-bit x86 kernels are only packaged for
> > amd64 and not x32 or i686, and 64-bit Arm kernels are only
> > packaged for arm64 but not armhf or formerly armel.  
> 
>  Weird, x32 vs x64 for the Intel ISA or say n32 vs n64 for the MIPS ISA 
> are psABI variants rather than architectures.  All are native, just using 
> different register usage conventions.

IIRC n32 just uses the 32bit system calls.
x32 can't do that due to the differing alignment of u64.
So the x86-64 kernel has to have three sets of system call wrappers (etc).

	David

> 
>  And the kernel is a bare metal application, it has nothing to do with the 
> userland as far as the user psABI is concerned.  It could use yet another 
> psABI and I suspect this is the case at least for some of the Linux ports 
> (`-mregparm=' GCC option comes immediately to mind).  Insisting that the 
> same compilation options are used for the kernel as with all the userland 
> packages in a distribution seems artificial and unreasonable to me.
> 
>  BTW, at least with n32 the MIPS architecture permits CPU implementations 
> that only support that psABI and not n64.  Never implemented, I believe, 
> but just proves its nativity.
> 
>  FWIW,
> 
>   Maciej
>