[PATCH v4 06/12] ARM: vfp: Remove workaround for Feroceon CPUs

[Linus Walleij]

On Mon, Mar 20, 2023 at 2:19 PM Ard Biesheuvel <ardb at kernel.org> wrote:

> Feroceon CPUs have a non-standard implementation of VFP which reports
> synchronous VFP exceptions using the async VFP flag. This requires a
> workaround which is difficult to reconcile with other implementations,
> making it tricky to support both versions in a single image.
>
> Since this is a v5 CPU, it is not supported by armhf and so the
> likelihood that anybody is using this with recent distros/kernels and
> rely on the VFP at the same time is extremely low. So let's just disable
> VFP support on these cores, so we can remove the workaround.
>
> This will help future development to support v5 and v6 CPUs with a
> single kernel image.
>
> Signed-off-by: Ard Biesheuvel <ardb at kernel.org>

I agree, I have one of those systems as my NAS, currently running
an (unsupported) version of ArchLinuxARM:

$ cat /proc/cpuinfo
processor    : 0
model name    : Feroceon 88FR131 rev 1 (v5l)
BogoMIPS    : 83.33
Features    : swp half thumb fastmult edsp
CPU implementer    : 0x56
CPU architecture: 5TE
CPU variant    : 0x2
CPU part    : 0x131
CPU revision    : 1

Hm doesn't even have any VFP, I don't know what spins of this Marvell
silicon that even does?
Reviewed-by: Linus Walleij <linus.walleij at linaro.org>

I think this is again on the level of a tree falling in the forest and no-one
being there to hear it, but let's page Nico again because I am pretty
sure if anyone worked with this it was him.

Yours,
Linus Walleij