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Sender: Richard Henderson <rth7680@gmail.com>
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Date: Wed, 05 Nov 2014 07:53:57 +0100
From: Richard Henderson <rth@twiddle.net>
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Subject: Re: [Qemu-devel] [PATCH] s390x: Implement SAM{24,31,64}
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To: Alexander Graf <agraf@suse.de>
Cc: kbastian@mail.uni-paderborn.de, qemu-devel@nongnu.org

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 <agraf@suse.de>

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 <rth@twiddle.net>


r~