Re: [PATCH] ARM: makefile: use ARMv3M mode for RiscPC

[Arnd Bergmann]

On Tue, Oct 2, 2018 at 3:28 PM Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote:
>
> On 2 October 2018 at 15:20, Jason A. Donenfeld <Jason@xxxxxxxxx> wrote:
> > The purpose of CONFIG_CPU_32v3 is to avoid ldrh/strh on the RiscPC,
> > which is pretty much an ARMv4 device, except its bus will choke on the
> > half-words. The way to make the C compiler not output ldrh/strh is with
> > -march=armv3, which doesn't support them in the ISA. However, this
> > prevents certain cryptography code from working that uses instructions
> > like umull. Fortunately there's also -march=armv3m that does support
> > those, making it possible to continue assembling optimized cryptography
> > routines for our beloved RiscPC.
> >
> > Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
> > Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> > Cc: Russell King <linux@xxxxxxxxxxxxxxx>
> > Cc: Arnd Bergmann <arnd@xxxxxxxx>
>
> Acked-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>

Acked-by: Arnd Bergmann <arnd@xxxxxxxx>

Please add this to Russell's patch tracker for inclusion at
http://www.arm.linux.org.uk/developer/patches/

      Arnd