Re: [PATCH] binfmt: Don't consider riscv{32,64} part of the same family

[Richard Henderson]

On 12/3/24 04:35, Peter Maydell wrote:
> On Tue, 3 Dec 2024 at 10:19, Daniel P. Berrangé <berrange@redhat.com> wrote:
> > Separatley this from patch, we should also consider whether
> > it is time to do the same for aarch64/arm7.
> >
> > If I look at this page:
> >
> >    https://gpages.juszkiewicz.com.pl/arm-socs-table/arm-socs.html
> >
> > and sort by 'announced' to see msot recent CPUs first, then
> > almost all of them have "NO" in the "aarch32 support" column.
> >
> > IOW, on modern aarch64 CPUs, qemu-arm is the only viable way
> > to run 32-bit usermode binaries AFAICT, and suggests we ought
> > to be creating a binfmt rule for that on aarch64 hosts.
>
> What happens if you have a host CPU that *does* support 32-bit
> natively and you also register the binfmt rule? Does the
> host kernel prefer to execute natively or does it invoke
> QEMU? I don't think we want to roll out something that
> silently downgrades native execution to emulation...

The registered rule applies and the kernel invokes qemu.


r~