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From: Paolo Bonzini <pbonzini@redhat.com>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: "qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [Qemu-devel] broken incoming migration
Date: Thu, 30 May 2013 09:49:51 +0200	[thread overview]
Message-ID: <51A7049F.6040207@redhat.com> (raw)
In-Reply-To: <51A7036A.3050407@ozlabs.ru>

Il 30/05/2013 09:44, Alexey Kardashevskiy ha scritto:
> Hi!
> 
> I found the migration broken on pseries platform, specifically, this patch
> broke it:
> 
> f1c72795af573b24a7da5eb52375c9aba8a37972
> migration: do not sent zero pages in bulk stage
> 
> The idea is not to send zero pages to the destination guest which is
> expected to have 100% empty RAM.
> 
> However on pseries plaftorm the guest always has some stuff in the RAM as a
> part of initialization (device tree, system firmware and rtas (?)) so it is
> not completely empty. As the source guest cannot detect this, it skips some
> pages during migration and we get a broken destination guest. Bug.
> 
> While the idea is ok in general, I do not see any easy way to fix it as
> neither QEMUMachine::init nor QEMUMachine::reset callbacks has information
> about whether we are about to receive a migration or not (-incoming
> parameter) and we cannot move device-tree and system firmware
> initialization anywhere else.
> 
> ram_bulk_stage is static and cannot be disabled from the platform
> initialization code.
> 
> So what would the community suggest?

Revert the patch. :)

Paolo

  parent reply	other threads:[~2013-05-30  7:50 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-05-30  7:44 [Qemu-devel] broken incoming migration Alexey Kardashevskiy
2013-05-30  7:49 ` Alexey Kardashevskiy
2013-05-30  7:49 ` Paolo Bonzini [this message]
2013-05-30  8:18   ` Alexey Kardashevskiy
2013-05-30  9:08     ` Peter Lieven
2013-05-30  9:31       ` Alexey Kardashevskiy
2013-05-30 13:00       ` Paolo Bonzini
2013-05-30 13:38         ` Alexey Kardashevskiy
2013-05-30 14:08           ` Paolo Bonzini
2013-05-30 14:38         ` Peter Lieven
2013-05-30 14:41           ` Paolo Bonzini
2013-06-04 13:52             ` Peter Lieven
2013-06-04 14:14               ` Paolo Bonzini
2013-06-04 14:38                 ` Peter Lieven
2013-06-04 14:40                   ` Paolo Bonzini
2013-06-04 14:48                     ` Peter Lieven
2013-06-04 15:17                       ` Paolo Bonzini
2013-06-04 19:15                         ` Peter Lieven
2013-06-05  3:37                           ` Alexey Kardashevskiy
2013-06-05  6:09                             ` Peter Lieven
2013-06-09  4:12                               ` liu ping fan
2013-06-09  7:22                                 ` Peter Lieven
2013-06-04 15:10                     ` Peter Lieven
2013-06-08  8:27                       ` Wenchao Xia
2013-06-08  8:30                         ` Alexey Kardashevskiy
2013-06-09  2:16                           ` Wenchao Xia
2013-06-09  2:34                             ` Alexey Kardashevskiy
2013-06-09  2:52                               ` [Qemu-devel] [Qemu-ppc] " Benjamin Herrenschmidt
2013-06-09  3:01                                 ` Alexey Kardashevskiy
2013-06-09  3:01                               ` [Qemu-devel] " Wenchao Xia
2013-06-09  3:09                                 ` Alexey Kardashevskiy
2013-06-09  3:31                                   ` Wenchao Xia
2013-06-09  7:27                                   ` Peter Lieven
2013-06-10  6:39                                     ` Alexey Kardashevskiy
2013-06-10  6:50                                       ` Peter Lieven
2013-06-10  6:55                                         ` Alexey Kardashevskiy
2013-06-10  8:44                                           ` Peter Lieven
2013-06-10  9:10                                             ` Alexey Kardashevskiy
2013-06-10  9:33                                               ` [Qemu-devel] [Qemu-ppc] " Benjamin Herrenschmidt
2013-06-10  9:42                                                 ` Peter Lieven
2013-06-09  2:53                             ` Benjamin Herrenschmidt
2013-06-12 14:00                               ` Paolo Bonzini
2013-06-12 14:11                                 ` Benjamin Herrenschmidt
2013-06-12 20:10                                   ` Paolo Bonzini
2013-06-13  2:41                                     ` Wenchao Xia
2013-06-03 10:04           ` [Qemu-devel] " Alexey Kardashevskiy
2013-06-04 10:56             ` Peter Lieven
2013-06-08  8:24         ` Wenchao Xia
2013-05-30 10:18 ` Peter Maydell

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