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Re: [Qemu-devel] [PATCH 07/10] target-s390x: enable fully implemented fa

From: Aurelien Jarno
Subject: Re: [Qemu-devel] [PATCH 07/10] target-s390x: enable fully implemented facilities
Date: Mon, 25 May 2015 23:13:47 +0200
User-agent: Mutt/1.5.23 (2014-03-12)

On 2015-05-25 23:04, Alexander Graf wrote:
> On 25.05.15 23:02, Aurelien Jarno wrote:
> > On 2015-05-25 22:39, Alexander Graf wrote:
> >>
> >>
> >> On 25.05.15 01:47, Aurelien Jarno wrote:
> >>> Cc: Alexander Graf <address@hidden>
> >>> Cc: Richard Henderson <address@hidden>
> >>> Signed-off-by: Aurelien Jarno <address@hidden>
> >>
> >> Shouldn't this get populated based on the selected -cpu type?
> > 
> > In the long term yes, but given we only implement one CPU type (or
> > rather none) in TCG mode, we can consider that's already the case.
> There are patches coming from IBM to at least add a list of a good
> number of s390x cpu types. I'd really like to make use of that and have
> actual CPU types selectable.

I guess they are for the KVM mode. Do they provide the corresponding 
facilities list? Probably otherwise that doesn't really differentiate
various CPUs. Please make sure of that when reviewing these patches.

> At least let's move towards that model. So the code in question should
> take the facility capabilities from the first cpu object (or the class?)
> for example and we bump it to the currently supported feature set in there.

Yes, that would work for STFL/STFLE, though we should have a list of
facilities implemented by TCG so we can mask out the non-implemented
facilities. This basically corresponds to the informations provided by
the current patch.

That said that won't work for actually disabling the corresponding
instructions as we don't have a 1 to 1 mapping between the facilities
and the group of instructions. Anyway we don't even check that right

Aurelien Jarno                          GPG: 4096R/1DDD8C9B
address@hidden                 http://www.aurel32.net

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