Re: [Qemu-devel] Boot order problem and disable iPXE/gPXE

[Gerhard Wiesinger <lists@wiesinger.com>]

On Thu, 5 Jan 2012, Gleb Natapov wrote:

> On Thu, Jan 05, 2012 at 10:27:44AM +0100, Gerhard Wiesinger wrote:
>> On Thu, 5 Jan 2012, Gleb Natapov wrote:
>>
>>> On Thu, Jan 05, 2012 at 10:09:44AM +0100, Gerhard Wiesinger wrote:
>>>> On Thu, 5 Jan 2012, Gleb Natapov wrote:
>>>>
>>>>> On Thu, Jan 05, 2012 at 09:23:02AM +0100, Gerhard Wiesinger wrote:
>>>>>> On Thu, 5 Jan 2012, Gerd Hoffmann wrote:
>>>>>>
>>>>>>> On 01/04/12 19:02, Gerhard Wiesinger wrote:
>>>>>>>> Hello,
>>>>>>>>
>>>>>>>> I'm having the following boot order problem using an SCSI option ROM:
>>>>>>>>
>>>>>>>
>>>>>>>> Still boots the cdrom instead of harddisk. So it is impossible to have a
>>>>>>>> bootable CDROM in the VM without booting from it.
>>>>>>>
>>>>>>> -option-rom romfile=/root/roms/8xx_64.rom,bootindex=1
>>>>>>
>>>>>> Ok, works well, but I think than "-boot order=c" is buggy, right?
>>>>>>
>>>>> Wrong. "-boot order=c" tells seabios to boot from a HD, but for that
>>>>> Seabios needs to actually know what is HD and what is not. Since Seabios
>>>>> does not support scsi controller natively it only sees pci device and
>>>>> has no idea that you have scsi disk there. It uses pci option rom to
>>>>> boot from this unknown device.
>>>>
>>>> But as far as I remember therefore the option ROM registers through
>>>> BIOS for INT 19h booting. So Seabios should know it that this is a
>>>> harddisk.
>>> It registers BEV. Otherwise you wouldn't be able to boot at all. In fact
>>> it registers multiple BEVs (one for each attached scsi device). But BIOS
>>> knows nothing about the device behind the BEV. It just jumps to BEV
>>> address to boot from it when INT 19h is called. There may be scsi cdrom
>>> there or even tape.
>>
>> But to get rid of this problem typical BIOSes have an option whether
>> they prefer to BOOT from SCSI (with an option ROM) or
>> from the other devices. Then the option ROM typically boots from the
>> first registered device.
>>
>> I think this is a missing feature in Seabios.
>>
> How is it missing if you just used it and confirmed that it worked?

It had to specify it on the option ROM itself. But I think a generic way 
would be e.g.:
boot=SCSI,c,a

Ciao,
Gerhard

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