From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Andreas Färber" <afaerber@suse.de>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
qemu-devel@nongnu.org, Alexander Graf <agraf@suse.de>,
qemu-ppc@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>,
Paul Mackerras <paulus@samba.org>,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [Qemu-devel] [RFC PATCH] spapr: support time base offset migration
Date: Fri, 06 Sep 2013 00:26:59 +1000 [thread overview]
Message-ID: <1378391219.4321.191.camel@pasglop> (raw)
In-Reply-To: <522891C2.8020107@suse.de>
On Thu, 2013-09-05 at 16:14 +0200, Andreas Färber wrote:
> Are you thinking of POWER8 having a different frequency than POWER8 in
> compat mode? Because migration from one -cpu to another is not supported
> elsewhere.
>
> Even if we want to migrate from one POWER7 revision to another, we
> should let the destination use the revision of the source (guest ABI!),
> via property if need be. Anything else will lead to confusion as to what
> is supported and what is not. That -cpu host is the default for
> convenience shouldn't relieve admins/libvirt to think about sensible
> setups like they have to on x86.
Besides POWER8 uses 512Mhz too :-) It's been architected so it's
unlikely to change from now on.
Cheers,
Ben.
> Andreas
>
> >
> > But yes, without frequency adjustment I see where you're coming from. We still only need the timebase the guest sees, not the offset. But we also need the host wall clock to allow for adjustments :).
> >
> >
> > Alex
> >
>
>
next prev parent reply other threads:[~2013-09-05 14:27 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-03 7:31 [Qemu-devel] [RFC PATCH] spapr: support time base offset migration Alexey Kardashevskiy
2013-09-03 8:42 ` Andreas Färber
2013-09-03 9:07 ` Alexey Kardashevskiy
2013-09-03 9:22 ` Andreas Färber
2013-09-04 1:13 ` Alexey Kardashevskiy
2013-09-04 1:27 ` Alexander Graf
2013-09-05 4:30 ` David Gibson
2013-09-05 4:54 ` Alexey Kardashevskiy
2013-09-05 9:16 ` Alexander Graf
2013-09-05 9:48 ` Alexey Kardashevskiy
2013-09-05 9:58 ` Alexander Graf
2013-09-05 11:44 ` Benjamin Herrenschmidt
2013-09-05 12:37 ` Alexander Graf
2013-09-05 13:36 ` Benjamin Herrenschmidt
2013-09-05 13:39 ` Alexander Graf
2013-09-05 14:14 ` Andreas Färber
2013-09-05 14:26 ` Benjamin Herrenschmidt [this message]
2013-09-05 15:11 ` Alexander Graf
2013-09-09 2:40 ` Alexey Kardashevskiy
2013-09-09 5:50 ` Alexander Graf
2013-09-09 5:58 ` Alexey Kardashevskiy
2013-09-09 6:06 ` Alexander Graf
2013-09-09 9:29 ` Benjamin Herrenschmidt
2013-09-09 9:32 ` Alexander Graf
2013-09-09 9:38 ` Benjamin Herrenschmidt
2013-09-09 9:41 ` Alexander Graf
2013-09-13 5:20 ` David Gibson
2013-09-13 18:06 ` Alexander Graf
2013-09-05 11:42 ` Benjamin Herrenschmidt
2013-09-05 12:09 ` Alexey Kardashevskiy
2013-09-06 3:00 ` David Gibson
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