From: Daniel Kiper <dkiper@net-space.pl>
To: Olaf Hering <olaf@aepfle.de>
Cc: kexec@lists.infradead.org, xen-devel@lists.xensource.com,
linux-kernel@vger.kernel.org
Subject: Re: incorrect layout of globals from head_64.S during kexec boot
Date: Fri, 6 Jul 2012 10:41:20 +0200 [thread overview]
Message-ID: <20120706084120.GA31219@router-fw-old.local.net-space.pl> (raw)
In-Reply-To: <20120705210607.GA26908@aepfle.de>
On Thu, Jul 05, 2012 at 11:06:07PM +0200, Olaf Hering wrote:
>
> During kexec in a Xen PVonHVM guest the new kernel crashes most of the
> time in secondary_startup_64 because the content of phys_base is
> corrupted. Its not zero as expected but has some random other values.
> While debugging that crash I came up with the change below to inspect
> the memory around phys_base.
>
> It turned out that the globales are not in the expected memory location.
> An expected value such as phys_base_plus1 is shifted, but by a different
> amount during repeated kexec attempts. Up to now I havent figured out
> where this happens.
>
> My question is: were to put additional debug to trace the copying of the
> data section to its final destination? Is this a task of kexec -l or
> does that happen during decompressing? I suspect the latter. This is the
> console output before the crash (the crash happens in 'movq %rax, %cr3'):
Copy is done a few times durnig kexec/kdump but the most important
in this case, I think, is in relocate_kernel() function (look for
rep movsl or rep movsq and code around it). But I am a bit surprised
that kernel is decompressing itself. I always thought that it is done
during kexec/kdump load phase but maybe I am wrong. Could you send
me more info about your Linux Kernel version, kexec-tools version
and exact commands which you are using to load/exececute kernel?
Daniel
WARNING: multiple messages have this Message-ID (diff)
From: Daniel Kiper <dkiper@net-space.pl>
To: Olaf Hering <olaf@aepfle.de>
Cc: xen-devel@lists.xensource.com, kexec@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: incorrect layout of globals from head_64.S during kexec boot
Date: Fri, 6 Jul 2012 10:41:20 +0200 [thread overview]
Message-ID: <20120706084120.GA31219@router-fw-old.local.net-space.pl> (raw)
In-Reply-To: <20120705210607.GA26908@aepfle.de>
On Thu, Jul 05, 2012 at 11:06:07PM +0200, Olaf Hering wrote:
>
> During kexec in a Xen PVonHVM guest the new kernel crashes most of the
> time in secondary_startup_64 because the content of phys_base is
> corrupted. Its not zero as expected but has some random other values.
> While debugging that crash I came up with the change below to inspect
> the memory around phys_base.
>
> It turned out that the globales are not in the expected memory location.
> An expected value such as phys_base_plus1 is shifted, but by a different
> amount during repeated kexec attempts. Up to now I havent figured out
> where this happens.
>
> My question is: were to put additional debug to trace the copying of the
> data section to its final destination? Is this a task of kexec -l or
> does that happen during decompressing? I suspect the latter. This is the
> console output before the crash (the crash happens in 'movq %rax, %cr3'):
Copy is done a few times durnig kexec/kdump but the most important
in this case, I think, is in relocate_kernel() function (look for
rep movsl or rep movsq and code around it). But I am a bit surprised
that kernel is decompressing itself. I always thought that it is done
during kexec/kdump load phase but maybe I am wrong. Could you send
me more info about your Linux Kernel version, kexec-tools version
and exact commands which you are using to load/exececute kernel?
Daniel
WARNING: multiple messages have this Message-ID (diff)
From: Daniel Kiper <dkiper@net-space.pl>
To: Olaf Hering <olaf@aepfle.de>
Cc: xen-devel@lists.xensource.com, kexec@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: incorrect layout of globals from head_64.S during kexec boot
Date: Fri, 6 Jul 2012 10:41:20 +0200 [thread overview]
Message-ID: <20120706084120.GA31219@router-fw-old.local.net-space.pl> (raw)
In-Reply-To: <20120705210607.GA26908@aepfle.de>
On Thu, Jul 05, 2012 at 11:06:07PM +0200, Olaf Hering wrote:
>
> During kexec in a Xen PVonHVM guest the new kernel crashes most of the
> time in secondary_startup_64 because the content of phys_base is
> corrupted. Its not zero as expected but has some random other values.
> While debugging that crash I came up with the change below to inspect
> the memory around phys_base.
>
> It turned out that the globales are not in the expected memory location.
> An expected value such as phys_base_plus1 is shifted, but by a different
> amount during repeated kexec attempts. Up to now I havent figured out
> where this happens.
>
> My question is: were to put additional debug to trace the copying of the
> data section to its final destination? Is this a task of kexec -l or
> does that happen during decompressing? I suspect the latter. This is the
> console output before the crash (the crash happens in 'movq %rax, %cr3'):
Copy is done a few times durnig kexec/kdump but the most important
in this case, I think, is in relocate_kernel() function (look for
rep movsl or rep movsq and code around it). But I am a bit surprised
that kernel is decompressing itself. I always thought that it is done
during kexec/kdump load phase but maybe I am wrong. Could you send
me more info about your Linux Kernel version, kexec-tools version
and exact commands which you are using to load/exececute kernel?
Daniel
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next prev parent reply other threads:[~2012-07-06 9:25 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-05 21:06 incorrect layout of globals from head_64.S during kexec boot Olaf Hering
2012-07-05 21:06 ` Olaf Hering
2012-07-06 8:29 ` [Xen-devel] " Jan Beulich
2012-07-06 8:29 ` Jan Beulich
2012-07-06 8:29 ` Jan Beulich
2012-07-06 8:41 ` Daniel Kiper [this message]
2012-07-06 8:41 ` Daniel Kiper
2012-07-06 8:41 ` Daniel Kiper
2012-07-06 12:07 ` Olaf Hering
2012-07-06 12:07 ` Olaf Hering
2012-07-06 12:56 ` [Xen-devel] " Jan Beulich
2012-07-06 12:56 ` Jan Beulich
2012-07-06 12:56 ` Jan Beulich
2012-07-06 13:31 ` Olaf Hering
2012-07-06 13:31 ` Olaf Hering
2012-07-06 13:31 ` Olaf Hering
2012-07-06 13:53 ` Jan Beulich
2012-07-06 13:53 ` Jan Beulich
2012-07-06 13:53 ` Jan Beulich
2012-07-06 14:14 ` Olaf Hering
2012-07-06 14:14 ` Olaf Hering
2012-07-06 14:50 ` Jan Beulich
2012-07-06 14:50 ` Jan Beulich
2012-07-06 14:50 ` Jan Beulich
2012-07-06 17:29 ` Olaf Hering
2012-07-06 17:29 ` Olaf Hering
2012-07-10 9:33 ` Olaf Hering
2012-07-10 9:33 ` Olaf Hering
2012-07-10 14:14 ` Konrad Rzeszutek Wilk
2012-07-10 14:14 ` Konrad Rzeszutek Wilk
2012-07-10 14:46 ` Ian Campbell
2012-07-10 14:46 ` Ian Campbell
2012-07-10 14:51 ` Konrad Rzeszutek Wilk
2012-07-10 14:51 ` Konrad Rzeszutek Wilk
2012-07-10 14:51 ` Konrad Rzeszutek Wilk
2012-07-10 15:29 ` Ian Campbell
2012-07-10 15:29 ` Ian Campbell
2012-07-10 15:29 ` Ian Campbell
2012-07-10 15:37 ` Olaf Hering
2012-07-10 15:37 ` Olaf Hering
2012-07-10 15:23 ` Olaf Hering
2012-07-10 15:23 ` Olaf Hering
2012-07-10 17:26 ` Konrad Rzeszutek Wilk
2012-07-10 17:26 ` Konrad Rzeszutek Wilk
2012-07-10 17:26 ` Konrad Rzeszutek Wilk
2012-07-10 18:09 ` Olaf Hering
2012-07-10 18:09 ` Olaf Hering
2012-07-10 18:32 ` Konrad Rzeszutek Wilk
2012-07-10 18:32 ` Konrad Rzeszutek Wilk
2012-07-10 19:08 ` Keir Fraser
2012-07-10 19:08 ` Keir Fraser
2012-07-10 19:08 ` Keir Fraser
2012-07-13 20:20 ` Olaf Hering
2012-07-13 20:20 ` Olaf Hering
2012-07-14 4:54 ` Keir Fraser
2012-07-14 4:54 ` Keir Fraser
2012-07-14 4:54 ` Keir Fraser
2012-07-15 16:06 ` Olaf Hering
2012-07-15 16:06 ` Olaf Hering
2012-07-15 17:17 ` Keir Fraser
2012-07-15 17:17 ` Keir Fraser
2012-07-15 17:17 ` Keir Fraser
2012-07-16 15:46 ` Konrad Rzeszutek Wilk
2012-07-16 15:46 ` Konrad Rzeszutek Wilk
2012-07-17 10:24 ` Olaf Hering
2012-07-17 10:24 ` Olaf Hering
2012-07-17 12:34 ` Olaf Hering
2012-07-17 12:34 ` Olaf Hering
2012-07-06 15:54 ` Daniel Kiper
2012-07-06 15:54 ` Daniel Kiper
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