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To: suparna@in.ibm.com
Cc: Andy Pfiffer <andyp@osdl.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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       Dave Hansen <haveblue@us.ibm.com>
Subject: Re: [ANNOUNCE][CFT] kexec for v2.5.48 && kexec-tools-1.7 -- Success Story!
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From: ebiederm@xmission.com (Eric W. Biederman)
Date: 20 Nov 2002 02:17:04 -0700
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Suparna Bhattacharya <suparna@in.ibm.com> writes:

> On Mon, Nov 18, 2002 at 05:10:38PM -0800, Andy Pfiffer wrote:
> > On Mon, 2002-11-18 at 00:53, Eric W. Biederman wrote:
> > > kexec is a set of systems call that allows you to load another kernel
> > > from the currently executing Linux kernel.  The current implementation
> > > has only been tested, and had the kinks worked out on x86, but the
> > > generic code should work on any architecture.
> > 
> > Great News, Eric.  For the first time *ever* I got a kexec reboot to
> > work on my most troublesome machine (see below).
> 
> Same here - preloading the new kernel and issuing kexec -e after 
> init 1 works on the troublesome SMP system I'd earlier been sending 
> you earlier. Bootimg used to work on this setup, so bypassing the 
> bios calls had the expected effect.
> 
> If I issue the call earlier though, it runs into trouble with aic7xxx
> reporting interrupts during setup. Guess you know why we are looking
> at that case - eventually need to be able to transition directly at dump 
> time without a chance to go through user-space shutdown ... 

The needed hooks are there.  You can make certain an appropriate
->shutdown()/reboot_notifier method is present, or you can fix the driver
so it can initialize the device from any random state.  

I really don't know what kinds of failures you hope to recover
from with the kexec on panic code, so I really can't comment on
how well things will work.  There will always be a set of failures
that are non-recoverable, but that doesn't mean there isn't a useful
subset.  Anyway there is certainly plenty of material for you to
experiment with and see what works usefully in practice.

Eric

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