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[Xen-devel] Re: [PATCH] Xen Guest Kexec

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] Re: [PATCH] Xen Guest Kexec
From: Horms <horms@xxxxxxxxxxxx>
Date: Thu, 23 Feb 2006 10:52:55 +0000 (UTC)
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Mark Williamson <mark.williamson@xxxxxxxxxxxx> wrote:
> All,
> I'm posting to the Xen-devel list and the OSDL fastboot list.  There are a 
> number of Xen folks who'll want to look at the code.  For the fastboot folks, 
> this is mostly intended as an announcement of the port.  Please limit your 
> replies to the list(s) that they applies to, thanks :-)
> A number of people have expressed interest in kexec support for Xen guests.  
> In particular, it's mainly useful for purposes of implementing an in-guest 
> bootloader app and avoiding the need for dom0 to access the guest filesystem.
> It's a largish patch, so I stuck it online: 
> http://www.cl.cam.ac.uk/~maw48/xenguest_kexec.patch
> Tested on i386.  I suspect it'll have build issues on x86_64 but those should 
> be easy to fix - actually the code is probably generic enough to work on 
> both.
> You'll also need a modified version of the kexec tools, which I'll post 
> details of later.
> Notes on the implementation:
> Kexec in a Xen guest doesn't work like on a real machine.  The guest relies 
> on 
> outside assistance to complete the job.  The guest communicates details of 
> the kexec to Xend.  Xend extracts the data from the guest's memory image and 
> uses it to rebuild the domain with a new kernel, etc.  This approach 
> simplifies the changes needed to support kexec and minimises code duplication 
> between Linux and the domain builder itself.
> Kexec-ing the whole host is a separate issue, I think it's best addressed 
> with 
> a port of kexec to Xen itself.


I have been looking into various crash-dump options, and with that in
mind, exploring kexec for Dom0. I'm wondering if the patch above is
still the latest, and if this is still the prefered approach
for kexec in Dom0.


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