[SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios

H. Peter Anvin hpa at zytor.com
Tue Oct 12 19:35:51 CEST 2010

On real hardware it is shared between BIOS and the OS, actually.

"Gleb Natapov" <gleb at redhat.com> wrote:

>On Tue, Oct 12, 2010 at 09:33:16AM -0700, H. Peter Anvin wrote:
>> On 10/12/2010 01:01 AM, Gleb Natapov wrote:
>> > On Mon, Oct 11, 2010 at 02:15:26PM -0700, H. Peter Anvin wrote:
>> >>> I don't disagree.
>> >>>
>> >>> I think the best thing to do is to let SeaBIOS create a boot order table 
>> >>> that contains descriptive information and then advertise that to QEMU.
>> >>>
>> >>> QEMU can then try to associate the list of bootable devices with it's 
>> >>> own set of devices and select a preferred order that it can then give 
>> >>> back to SeaBIOS.  SeaBIOS can then present that list to the user for 
>> >>> additional refinement.
>> >>
>> >> Really, this kind of comes down to having a data structure that anything
>> >> (Qemu, SeaBIOS and if needed the guest OS) can read and modify as needed.
>> >>
>> > But then QEMU and seabios will have to have shared storage they can
>> > both write too. And this shared storage is part of VM now so you need
>> > to carry it around when you move your VM elsewhere.
>> >  
>> Yes, and it's part of real hardware, too.  It's usually called "the
>> CMOS", short for CMOS RAM.
>On real hardware it is not shared between HW and bios. It is
>written/read only by BIOS. In qemu it is not persistent and generated
>for each qemu invocation. Previously it was used to pass config params
>from qemu to a bios (and some legacy params are still passed that way),
>but we moved to better interface for that (firmware config).
>			Gleb.

Sent from my mobile phone.  Please pardon any lack of formatting.

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