linux-kernel - Re: [PATCH v2 01/11] kexec: introduce kexec

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Message-ID: <18e831d4-910d-4f58-8911-1398b96e3a47@email.android.com>
Date:	Thu, 22 Nov 2012 17:38:33 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andrew Cooper <andrew.cooper3@...rix.com>
CC:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Daniel Kiper <daniel.kiper@...cle.com>,
	"jbeulich@...e.com" <jbeulich@...e.com>,
	"konrad.wilk@...cle.com" <konrad.wilk@...cle.com>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"x86@...nel.org" <x86@...nel.org>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"virtualization@...ts.linux-foundation.org" 
	<virtualization@...ts.linux-foundation.org>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>
Subject: Re: [PATCH v2 01/11] kexec: introduce kexec_ops struct

I still don't really get why it can't be isolated from dom0, which would make more sense to me, even for a Xen crash.

Andrew Cooper <andrew.cooper3@...rix.com> wrote:

>On 22/11/2012 17:47, H. Peter Anvin wrote:
>> The other thing that should be considered here is how utterly 
>> preposterous the notion of doing in-guest crash dumping is in a
>system 
>> that contains a hypervisor.  The reason for kdump is that on bare
>metal 
>> there are no other options, but in a hypervisor system the right
>thing 
>> should be for the hypervisor to do the dump (possibly spawning a
>clean 
>> I/O domain if the I/O domain is necessary to access the media.)
>>
>> There is absolutely no reason to have a crashkernel sitting around in
>
>> each guest, consuming memory, and possibly get corrupt.
>>
>> 	-hpa
>>
>
>(Your reply to my email which I can see on the xen devel archive
>appears
>to have gotten lost somewhere inside the citrix email system, so
>apologies for replying out of order)
>
>The kdump kernel loaded by dom0 is for when Xen crashes, not for when
>dom0 crashes (although a dom0 crash does admittedly lead to a Xen
>crash)
>
>There is no possible way it could be a separate domain; Xen completely
>ceases to function as soon as jumps to the entry point of the kdump
>image.
>
>~Andrew

-- 
Sent from my mobile phone. Please excuse brevity and lack of formatting.
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