Re: [PATCH v1 0/2] s390x/cpumodel: Introduce "best" model variants

From: Peter Maydell <peter.maydell@linaro.org>
To: David Hildenbrand <david@redhat.com>
Cc: "Thomas Huth" <thuth@redhat.com>,
	"Daniel P . Berrangé" <berrange@redhat.com>,
	"Janosch Frank" <frankja@linux.ibm.com>,
	"Cornelia Huck" <cohuck@redhat.com>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"QEMU Developers" <qemu-devel@nongnu.org>,
	"Markus Armbruster" <armbru@redhat.com>,
	"Halil Pasic" <pasic@linux.ibm.com>,
	"Christian Borntraeger" <borntraeger@de.ibm.com>,
	qemu-s390x <qemu-s390x@nongnu.org>,
	"Michael Mueller" <mimu@linux.ibm.com>,
	"Jiri Denemark" <jdenemar@redhat.com>,
	"Eduardo Habkost" <ehabkost@redhat.com>
Subject: Re: [PATCH v1 0/2] s390x/cpumodel: Introduce "best" model variants
Date: Fri, 8 Nov 2019 11:10:55 +0000	[thread overview]
Message-ID: <CAFEAcA-mD3-Zg2JunGpMqbcaT1qboCenhqEFytZD0FmFcL2i9Q@mail.gmail.com> (raw)
In-Reply-To: <20191108110714.7475-1-david@redhat.com>

On Fri, 8 Nov 2019 at 11:08, David Hildenbrand <david@redhat.com> wrote:
>
> There was recently a discussion regarding CPU model versions. That concept
> does not fit s390x where we have a lot of feature variability. I
> proposed an alternative approach in [1], which might work for x86 as well
> (but I am not sure if x86 still can or wants to switch to that), and
> requires no real changes in upper layers.
>
> [1] and patch #2 contains more information on the motivation for this.
>
> E.g., specifying/expanding "z14-best" will result in the "best feature
> set possible on this accelerator, hw and, firmware". While a "z13" does
> not work under TCG and some z/VM versions, "z13-best" will work.

I think other architectures call this concept "max", not "best".
If we can manage some cross-architecture consistency that would
be helpful, but is s390x using 'max' already for something else?

thanks
-- PMM