Re: [Qemu-devel] [Qemu-ppc] Qemu boot device precedence over nvram boot-device setting

[Avik Sil <aviksil@linux.vnet.ibm.com>]

>>>> 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.
>>
> -boot has not enough verbosity to tell the device to boot from if you
> have more than one device of each type. What are you going to boot from
> if you have two disks, two NICs, etc?

Yes, -boot has this limitation and -boot is what we are currently using. 
We are extending this using the nvram boot-device property. With the 
nvram driver in place, we would be booting from boot-device. We also 
need a way from qemu to override this, where we hit this issue of the 
default boot device. And currently SLOF boots from the first disk/cdrom 
it discovers in device tree in case there are multiple disks or cdroms.

Regards,
Avik

>
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> 			Gleb.
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