Re: [Qemu-devel] [PATCH 2/2] risu_ppc64le: distinguish real illegal instruction

[Nikunj A Dadhania]

Peter Maydell <address@hidden> writes:

> On 13 February 2017 at 08:59, Nikunj A Dadhania
> <address@hidden> wrote:
>> While executing qemu_ppc64le, found an issue that the real illegal
>> instructions are handled as risu_op which results in wrong info at the
>> master end. Even the master needs to distinguish real illegal
>> instructions versus risu_op.
>>
>> Signed-off-by: Nikunj A Dadhania <address@hidden>
>
> No, this is deliberate. Otherwise you can't test illegal
> instructions. What should happen is that both master and
> apprentice ends end up in the default case, which does
> a register info compare and continues having stepped the
> PC past the illegal insn.

One of the issue that I had was some of the instruction are implemented
in the master and not in apprentice. I think we could then disable them
in the ppc64.risu. And enable them only when we have that implemented it
in qemu tcg.

> (If only one end thinks the insn is illegal then there will
> be a register mismatch on the PC.)

Yeah, the issue here was it does not come out obviously that there was a
real illegal instruction. Maybe a error print at both the ends would
help in debugging.

Regards
Nikunj