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Date: Thu, 04 Oct 2012 17:48:44 +0530
From: Avik Sil <aviksil@linux.vnet.ibm.com>
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Subject: Re: [Qemu-devel] [Qemu-ppc] Qemu boot device precedence over nvram
 boot-device setting
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To: Alexander Graf <agraf@suse.de>
Cc: Benjamin Herrenschmidt <benh@au1.ibm.com>, "qemu-ppc@nongnu.org List" <qemu-ppc@nongnu.org>, Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>, Gleb Natapov <gleb@redhat.com>, qemu-devel qemu-devel <qemu-devel@nongnu.org>

>>>> I looked at the bootindex stuff and found that when the bootindex is
>>>> specified for the disk and cdrom it generates a string like:
>>>>
>>>> "/spapr-vio-bridge/spapr-vscsi/channel@0/disk@0,1
>>>> /spapr-vio-bridge/spapr-vscsi/channel@0/disk@0,0"
>>>>
>>>> Now converting/translating this to OF device path is going to be
>>>> much trickier and might not be proper. So I propose a simple
>>>> solution by introducing a global flag that checks if explicit -boot
>>>> parameter is provided or not. The presence of this parameter is
>>>> verified in SLOF firmware. The flag had to be introduced as
>>>> boot_devices defaults to "cad" instead of null and passed to
>>>> machine->init().
>>>>
>>> So you want to hack around the problem. If -boot is specified what
>>> device are you going to boot from?
>>
>> It is going to boot from the device specified in -boot as default_boot_order is set to 0 in that case.
>
> Imagine you have 2 controllers:
>
>    * vio
>    * virtio
>
> and you specify -boot c. Which device are you going to boot from?

Currently, by default SLOF boots from the first disk it discovers in the 
device tree.

Regards,
Avik

>
>
> Alex
>
>