Re: [Qemu-devel] [PATCH] s390x: Implement SAM{24,31,64}

[Richard Henderson]

On 11/04/2014 09:19 PM, Alexander Graf wrote:
> The SAM instructions simply change 2 bits in PSW.MASK to advertise
> the current memory mode. While we can't fully guarantee that 31 bit
> mode (or even remotely 24 bit mode) actually work correctly, we don't
> check whether lpswe modifies these bits, so we shouldn't keep the
> guest from executing SAM instructions either.
> 
> This patch implements all SAM instrutions with their actual PSW changing
> semantics, making more recent Linux kernels boot properly which do issue
> a SAM31 call during early boot.
> 
> Signed-off-by: Alexander Graf <address@hidden>

Ho hum.  Reminds me that I should revive my tgt-s390 branch that
got bogged down last year on facilities management.

I think this is technically missing a SPECIFICATION exception if
the PC is out of range for the new mode.  But otherwise...

Reviewed-by: Richard Henderson <address@hidden>


r~