Re: [RFC PATCH v3 1/5] ppc64: Add semihosting support

[Leandro Lupori]

On 4/20/22 15:05, Peter Maydell wrote:
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> On Mon, 18 Apr 2022 at 20:15, Leandro Lupori
> <leandro.lupori@eldorado.org.br> wrote:
> > Add semihosting support for PPC64. This implementation is
> > based on the standard for ARM semihosting version 2.0, as
> > implemented by QEMU and documented in
> >
> >      https://github.com/ARM-software/abi-aa/releases
> >
> > The PPC64 specific differences are the following:
> >
> > Semihosting Trap Instruction: sc 7
> > Operation Number Register: r3
> > Parameter Register: r4
> > Return Register: r3
> > Data block field size: 64 bits
> >
> > +static inline bool
> > +common_semi_sys_exit_extended(CPUState *cs, int nr)
> > +{
> > +    return (nr == TARGET_SYS_EXIT_EXTENDED || sizeof(target_ulong) == 8);
> > +}
>
> Does the PPC specification for semihosting really follow the
> legacy Arm requirement that the 32-bit version of the EXIT
> call doesn't let the caller specify the exit status? It's
> not a very sensible choice IMHO if you don't have the legacy
> baggage to deal with.

As we are actually writing an unofficial PPC specification for 
semihosting now, I guess it makes sense to leave the legacy 32-bit 
version of EXIT out of it. I'll change this part to always return true.
By the way, this initial implementation supports only 64-bit PPC.

Thanks,
Leandro

> -- PMM