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From: Kevin Wolf <kwolf@suse.de>
To: Jamie Lokier <jamie@shareable.org>
Cc: qemu-devel@nongnu.org, kvm-devel <kvm@vger.kernel.org>,
	Laurent Vivier <laurent@lvivier.info>
Subject: Re: [Qemu-devel] qcow2 corruption observed,	fixed by reverting old change
Date: Wed, 11 Feb 2009 13:41:33 +0100	[thread overview]
Message-ID: <4992C77D.4030104@suse.de> (raw)
In-Reply-To: <20090211114126.GC31997@shareable.org>

Jamie Lokier schrieb:
> Kevin Wolf wrote:
>> Jamie Lokier schrieb:
>>> Although there are many ways to make Windows blue screen in KVM, in
>>> this case I've narrowed it down to the difference in
>>> qemu/block-qcow2.c between kvm-72 and kvm-73 (not -83).
>> This must be one of SVN revisions 5003 to 5008 in upstream qemu. Can you
>> narrow it down to one of these? I certainly don't feel like reviewing
>> all of them once again.
> 
> It's QEMU SVN delta 5005-5006, copied below.
> 
> I've tested by applying the diffs up to QEMU SVN revs 5003 to 500,
> onto kvm-72, and 5005-5006 is the diff which triggers the failed guest
> boot, consistently.

That's exactly what I was afraid of... It's the most difficult patch of
the series. I'm adding Laurent to CC who wrote the patch series then,
but I can imagine he wants to do different things in his spare time.

Besides reviewing the code over and over again, I think the only real
chance is that you can get a non-productive copy of your image and add
some debug code so that we can see at least which code path is causing
problems.

> Aside from logic, the code mixes signed 32-bit with unsigned 64-bit
> with unclear naming which would make me nervous.  My host is 64-bit,
> by the way.

I would suspect that simply having a 64 bit host isn't enough to trigger
the problem. These patches were in for half a year now without anyone
noticing such failure.

By the way and completely off-topic: Have you already tried to use the
VHD patches? I would really like to know if they fix your problems.

Kevin

WARNING: multiple messages have this Message-ID
From: Kevin Wolf <kwolf@suse.de>
To: Jamie Lokier <jamie@shareable.org>
Cc: Laurent Vivier <laurent@lvivier.info>,
	qemu-devel@nongnu.org, kvm-devel <kvm@vger.kernel.org>
Subject: Re: [Qemu-devel] qcow2 corruption observed,	fixed by reverting old change
Date: Wed, 11 Feb 2009 13:41:33 +0100	[thread overview]
Message-ID: <4992C77D.4030104@suse.de> (raw)
In-Reply-To: <20090211114126.GC31997@shareable.org>

Jamie Lokier schrieb:
> Kevin Wolf wrote:
>> Jamie Lokier schrieb:
>>> Although there are many ways to make Windows blue screen in KVM, in
>>> this case I've narrowed it down to the difference in
>>> qemu/block-qcow2.c between kvm-72 and kvm-73 (not -83).
>> This must be one of SVN revisions 5003 to 5008 in upstream qemu. Can you
>> narrow it down to one of these? I certainly don't feel like reviewing
>> all of them once again.
> 
> It's QEMU SVN delta 5005-5006, copied below.
> 
> I've tested by applying the diffs up to QEMU SVN revs 5003 to 500,
> onto kvm-72, and 5005-5006 is the diff which triggers the failed guest
> boot, consistently.

That's exactly what I was afraid of... It's the most difficult patch of
the series. I'm adding Laurent to CC who wrote the patch series then,
but I can imagine he wants to do different things in his spare time.

Besides reviewing the code over and over again, I think the only real
chance is that you can get a non-productive copy of your image and add
some debug code so that we can see at least which code path is causing
problems.

> Aside from logic, the code mixes signed 32-bit with unsigned 64-bit
> with unclear naming which would make me nervous.  My host is 64-bit,
> by the way.

I would suspect that simply having a 64 bit host isn't enough to trigger
the problem. These patches were in for half a year now without anyone
noticing such failure.

By the way and completely off-topic: Have you already tried to use the
VHD patches? I would really like to know if they fix your problems.

Kevin

  reply	other threads:[~2009-02-11 12:34 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-02-11  7:00 Jamie Lokier
2009-02-11  7:00 ` [Qemu-devel] " Jamie Lokier
2009-02-11  9:57 ` Kevin Wolf
2009-02-11 11:27   ` Jamie Lokier
2009-02-11 11:27     ` Jamie Lokier
2009-02-11 11:41   ` Jamie Lokier
2009-02-11 11:41     ` Jamie Lokier
2009-02-11 12:41     ` Kevin Wolf [this message]
2009-02-11 12:41       ` Kevin Wolf
2009-02-11 16:48       ` Jamie Lokier
2009-02-11 16:48         ` Jamie Lokier
2009-02-12 22:57         ` Consul
2009-02-12 22:57           ` [Qemu-devel] " Consul
2009-02-12 23:19           ` Consul
2009-02-12 23:19             ` [Qemu-devel] " Consul
2009-02-13  7:50             ` Marc Bevand
2009-02-16 12:44         ` [Qemu-devel] " Kevin Wolf
2009-02-17  0:43           ` Jamie Lokier
2009-02-17  0:43             ` Jamie Lokier
2009-03-06 22:37         ` Filip Navara
2009-03-06 22:37           ` Filip Navara
2009-02-12  5:45       ` Chris Wright
2009-02-12  5:45         ` Chris Wright
2009-02-12 11:08         ` Johannes Schindelin
2009-02-12 11:08           ` Johannes Schindelin
2009-02-13  6:41 ` Marc Bevand
2009-02-13 11:16   ` Kevin Wolf
2009-02-13 11:16     ` [Qemu-devel] " Kevin Wolf
2009-02-13 16:23     ` Jamie Lokier
2009-02-13 16:23       ` Jamie Lokier
2009-02-13 18:43       ` Chris Wright
2009-02-13 18:43         ` Chris Wright
2009-02-14  6:31       ` Marc Bevand
2009-02-14 22:28         ` Dor Laor
2009-02-14 22:28           ` Dor Laor
2009-02-15  2:27           ` Jamie Lokier
2009-02-15  7:56           ` Marc Bevand
2009-02-15  7:56             ` Marc Bevand
2009-02-15  2:37         ` Jamie Lokier
2009-02-15 10:57     ` Gleb Natapov
2009-02-15 10:57       ` [Qemu-devel] " Gleb Natapov
2009-02-15 11:46       ` Marc Bevand
2009-02-15 11:46         ` [Qemu-devel] " Marc Bevand
2009-02-15 11:54         ` Marc Bevand
2009-02-15 11:54           ` [Qemu-devel] " Marc Bevand

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