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To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Werner Almesberger <wa@almesberger.net>,
       Suparna Bhattacharya <suparna@in.ibm.com>,
       Jeff Garzik <jgarzik@pobox.com>,
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Subject: Re: [lkcd-devel] Re: What's left over.
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From: ebiederm@xmission.com (Eric W. Biederman)
Date: 05 Nov 2002 19:48:58 -0700
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Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

> On Tue, 2002-11-05 at 18:00, Werner Almesberger wrote:
> > Yes, I've just checked with Eric, and he hasn't received any
> > indication from Linus so far. I posted a reminder to linux-kernel.
> > I'd really hate to see kexec miss 2.6.
> 
> Let me ask the same dumb question - what does kexec need that a dumper
> doesn't. In other words given reboot/trap hooks can kexec happily live
> as a standalone module ?

Kexec primarily needs the reboot/trap hooks in working order, and exported,
for it to live externally to the kernel.  

Currently the reboot_notifier call chain is private to sys.c, and is not
exported even to other parts of the kernel.

Even together device_shutdown, and the reboot_notifier do not properly shutdown
the cpus on an SMP system.

Plus we are missing quite a ->shutdown methods at random in the kernel, and if
kexec is not easily available someone might not get around to writing
and debugging them.

Plus a system call seems the natural interface for something that
appears to be a reboot.

Eric
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