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From: Jim Mattson <jmattson@google.com>
Date: Thu, 1 Nov 2018 12:41:42 -0700
Message-ID: <CALMp9eSEtzJ05fBoyXNaaepFtH2+BepoLocNFm1xXvJfdS0zfg@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [Qemu-devel] [QEMU PATCH v2 0/2]: KVM: i386: Add support for
 save and restore nested state
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To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Liran Alon <liran.alon@oracle.com>, Paolo Bonzini <pbonzini@redhat.com>, Eduardo Habkost <ehabkost@redhat.com>, kvm list <kvm@vger.kernel.org>, mtosatti@redhat.com, qemu-devel@nongnu.org, rth@twiddle.net

On Thu, Nov 1, 2018 at 12:07 PM, Dr. David Alan Gilbert
<dgilbert@redhat.com> wrote:

> OK; the tricky thing is when you upgrade one host in a small cluster as
> you start doing an upgrade, and then once it's got it's first VM you
> can't migrate away from it until others are updated; that gets messy.

One must always be able to migrate off of kernel N+1 back to kernel N.
We depend on that whenever we have to rollback a kernel upgrade.