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Date:   Tue, 11 Dec 2018 15:30:17 +0000
From:   Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= <berrange@redhat.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Eduardo Habkost <ehabkost@redhat.com>,
        Borislav Petkov <bp@alien8.de>,
        =?utf-8?B?SsO2cmcgUsO2ZGVs?= <joro@8bytes.org>,
        Andre Przywara <andre.przywara@arm.com>,
        kvm ML <kvm@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Eric Blake <eblake@redhat.com>
Subject: Re: kvm: RDTSCP on AMD
Message-ID: <20181211153017.GN921@redhat.com>
Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= <berrange@redhat.com>
References: <20181210181328.GA762@zn.tnic>
 <20181210183730.GJ4669@habkost.net>
 <20181210184153.GB5482@zn.tnic>
 <20181210190600.GK4669@habkost.net>
 <20181210194258.GD5482@zn.tnic>
 <20181210200843.GN4669@habkost.net>
 <20181211103839.GC921@redhat.com>
 <20181211115546.GQ4669@habkost.net>
 <e4d9a943-2de2-34a7-3f52-ee3d64ea889a@redhat.com>
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On Tue, Dec 11, 2018 at 04:23:51PM +0100, Paolo Bonzini wrote:
> On 11/12/18 12:55, Eduardo Habkost wrote:
> >>   - Debian Jessie: 4.5
> >>   - Debian Stretch: 4.5
> >>   - RHEL-7: 3.10
> >>   - Ubuntu LTS (Xenial): 4.5
> >>   - OpenSUSE Leap 15: 4.12.14
> >>
> >> So we can't require Linux 4.5 as a minimum version at this time.
> > I'd like us to take a step back and consider what exactly
> > "support" means here.  QEMU will still work on older kernels if
> > we add RDTSCP to the CPU models, but at the same time I would
> > like to document that our strict runnability guarantees may not
> > be kept if running Linux < 4.5.
> 
> Anyway RHEL does have RDTSC support for AMD, and a bunch of other stuff.
>  The frankenkernel's KVM is somewhere between 4.5 and 4.10, with a dash
> of 4.20 of course. :)

Great, then, this is a non-issue - we just need to mention that fact
in the commit that sets the min version for the kernel 

Regards,
Daniel
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