Date: Tue, 30 Jul 2013 14:12:32 +0200
From: Daniel Kiper <daniel.kiper@oracle.com>
To: Matt Wilson <msw@amazon.com>
Cc: Daniel Kiper <dkiper@net-space.pl>, gregkh@linuxfoundation.org,
        abyde@acunu.com, brandon@ifup.org, ebiederm@xmission.com,
        grzegorz.milos@gmail.com, konrad.wilk@oracle.com, tim@acunu.com,
        linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        xen-devel@lists.xensource.com, kexec@lists.infradead.org
Subject: Re: [PATCH] kexec/kdump implementation for Xen PV domU
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On Mon, Jul 29, 2013 at 02:44:19PM -0700, Matt Wilson wrote:
> On Mon, Jul 29, 2013 at 07:15:43PM +0200, Daniel Kiper wrote:
> > Hi all,
> >
> > Here I am sending as attachments patches enabling kexec/kdump
> > support in Xen PV domU. Only x84_64 architecture is supported.
> > There is no support for i386 but some code could be easily reused.
> > Here is a description of patches:
>
> [...]
>
> >   - kexec-kernel-only_20121203.patch: this patch fixes timer
> >     issue on Amazon EC2 machines.
>
> Hi Daniel,
>
> Do you know the cause of this issue? Does it have something to do with
> singleshot timer migration when offlining/onlining SMP CPUs?

Sadly, no. I was not able to replicate this on my machines (I did test
on Xen 4.1). However, as I saw this issue appears on Xen 3.4 and 4.0
(IIRC version numbers used on your machines). Additionally, it does not
depend on CPU models. And it appears quite often but not always.
Maybe it is linked with singleshot timer migration.

Daniel
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