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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Wed, 17 Oct 2012 07:07:53 +1100
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Subject: Re: [Qemu-devel] nvram and boot order
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To: Anthony Liguori <aliguori@us.ibm.com>
Cc: Avik Sil <aviksil@linux.vnet.ibm.com>, David Gibson <david@gibson.dropbear.id.au>, qemu-devel@nongnu.org, Alex Graf <agraf@suse.de>

On Tue, 2012-10-16 at 14:55 -0500, Anthony Liguori wrote:
> 
> 4) If -boot is specified, the parameter should alter the contents of
>    NVRAM to change the boot order to what is specified by -boot.
> 
> 5) If ,bootorder is specified, it should take predence over -boot.
> 
> 6) ,bootorder= should also alter the contents of NVRAM to determine
> the
>    boot order

That's where I disagree. At least for us... I don't see why -boot or
-bootorder should alter the nvram content.

The plan is to have the nvram content essentially in control of SLOF
(ie. the BIOS in x86 land). Qemu doesn't know much of anything appart
from providing the storage for it.

I see -boot and -bootorder as ways to *temporarily* override whatever
setting was put in nvram by the guest. The nvram is typically populated
by the distro installer (though sometimes by hand by the user). One may
want to just temporarily boot from a CD (rescue for example, or to test
a live CD or something ...), that doesn't mean the permanent setting
should be altered.

I would pass -boot and -bootorder to SLOF like we pass the current
bootlist today and let it deal with it, I wouldn't touch the nvram.

Cheers,
Ben.