Re: [PATCH] target/hppa: Fix fid instruction emulation

[Helge Deller]

On 10/27/22 11:48, Richard Henderson wrote:
> On 10/27/22 16:31, Helge Deller wrote:
> > The fid instruction (Floating-Point Identify) puts the FPU model and
> > revision into the Status Register. Since those values shouldn't be 0,
> > store values there which a PCX-L2 (for 32-bit) or a PCX-W2 (for 64-bit)
> > would return.
> >
> > Signed-off-by: Helge Deller <deller@gmx.de>
> >
> > diff --git a/target/hppa/insns.decode b/target/hppa/insns.decode
> > index c7a7e997f9..3ba5f9885a 100644
> > --- a/target/hppa/insns.decode
> > +++ b/target/hppa/insns.decode
> > @@ -388,10 +388,8 @@ fmpyfadd_d      101110 rm1:5 rm2:5 ... 0 1 ..0 0 0 neg:1 
> > t:5    ra3=%rc32
> >
> >   # Floating point class 0
> >
> > -# FID.  With r = t = 0, which via fcpy puts 0 into fr0.
> > -# This is machine/revision = 0, which is reserved for simulator.
>
> Is there something in particular for which this is failing?
> Per the manual, 0 means simulator, which we are.

I can't say yet if it's really failing.
I noticed it while trying to get MPE/iX installed in a hppa guest.
In some doc (sorry don't know which one right now) I saw that 0/0
values were illegal values, which is why I changed the values to
become those of a PA7300LC CPU from a  B160L machine (which
we currently emulate with the hppa SeaBIOS).

> So far we haven't identified as a particular cpu, have we?

Not really, but as just mentioned the SeaBIOS reports back a B160L.
If we support more machines this needs to be adjusted.

> > +static bool trans_fid_f(DisasContext *ctx, arg_fid_f *a)
> > +{
> > +    nullify_over(ctx);
> > +#if TARGET_REGISTER_BITS == 64
> > +    save_frd(0, tcg_const_i64(0x13080000000000)); /* PA8700 (PCX-W2) */
> > +#else
> > +    save_frd(0, tcg_const_i64(0x0f080000000000)); /* PA7300LC (PCX-L2) */
> > +#endif
> > +    return nullify_end(ctx);
> > +}
>
> Missing ULL suffix.

Will fix.

Helge