From: Eduardo Habkost <ehabkost@redhat.com>
To: Vincent Bernat <vincent@bernat.im>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Richard Henderson <rth@twiddle.net>,
qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] target-i386: add pcid to both Sandy Bridge and Ivy Bridge
Date: Mon, 8 Jan 2018 20:28:53 -0200 [thread overview]
Message-ID: <20180108222853.GL6646@localhost.localdomain> (raw)
In-Reply-To: <m38td89ej7.fsf@luffy.cx>
On Mon, Jan 08, 2018 at 11:22:36PM +0100, Vincent Bernat wrote:
> ❦ 8 janvier 2018 20:14 -0200, Eduardo Habkost <ehabkost@redhat.com> :
>
> >> What are the consequences of running a too old kernel? Would KVM just
> >> hide PCID flag?
> >
> > On an old kernel, the SandyBridge and IvyBridge CPU models will
> > be unexpectedly become not runnable.
>
> But, isn't it the same for more recent models that already have PCID
> enabled?
Yes, the more recent models are already not runnable on those
hosts. The key here is "unexpectedly": management software can
assume that the CPU model won't become unrunnable when it was
runnable in the past, and logic that decides if/where a VM can be
started (or migrated to) might break.
--
Eduardo
next prev parent reply other threads:[~2018-01-08 22:29 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-08 20:50 [Qemu-devel] [PATCH] target-i386: add pcid to both Sandy Bridge and Ivy Bridge Vincent Bernat
2018-01-08 21:16 ` Eduardo Habkost
2018-01-08 21:51 ` Vincent Bernat
2018-01-08 22:14 ` Eduardo Habkost
2018-01-08 22:22 ` Vincent Bernat
2018-01-08 22:28 ` Eduardo Habkost [this message]
2018-01-08 22:37 ` Paolo Bonzini
2018-01-08 22:56 ` Eduardo Habkost
2018-01-08 23:09 ` Paolo Bonzini
2018-01-08 23:19 ` Eduardo Habkost
2018-01-09 7:04 ` Vincent Bernat
2018-01-09 6:41 ` Vincent Bernat
2018-01-09 6:40 ` Vincent Bernat
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