Xen devel - Mar 2009 - [Patch][RFC] BIOS: configure bootable pass-through device

Hi,

These patches allow users to configure bootable device in guest configration
file.
The shadow memory, which mean memory area loading option ROM, is small.
So if we specified many pass-through device, hvmloader cannot load all of option
ROM.
We want to select a device which we want to load the option ROM.
After applying these patches, we need to specify pci option of bootable device
like below.

pci = [ ''01:00.0,boot=1'' ]

boot=1 means bootable, boot=0 and no boot option mean non-bootable.

BTW, if we don''t specify the boot=1 option, we can boot from emulation
disks
and we can boot faster because option ROM is not initialized.

These patches use cmos(0x60) as a place retaining the devfn of bootable device.
Bochs BIOS doesn''t seems to use the offset 0x60.
What do you think of using cmos(0x60)?
Do you have some ideas?

Signed-off-by: Akio Takebe <takebe_akio@jp.fujitsu.com>

Best Regards,

Akio Takebe



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On 12/03/2009 10:11, "Akio Takebe" <takebe_akio@jp.fujitsu.com>
wrote:
> These patches use cmos(0x60) as a place retaining the devfn of bootable
> device.
> Bochs BIOS doesn''t seems to use the offset 0x60.
> What do you think of using cmos(0x60)?
> Do you have some ideas?
This shouldn''t need to touch qemu at all. This is a config option that
should be parsed by xm/xend and passed directly off to hvmloader. Passing it
via hvm_info_table would make most sense in my opinion. In which case you
need to probably pass it as an optional param to xc.hvm_build() and poke it
into hvm_info_table from that Python C wrapper function.

If not specified, should you keep default behaviour and try to load all
option ROMs? I''m not fussed - it''s just a thought.

 -- Keir



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Hi,

Keir Fraser wrote:
> On 12/03/2009 10:11, "Akio Takebe"
<takebe_akio@jp.fujitsu.com> wrote:
> 
>> These patches use cmos(0x60) as a place retaining the devfn of bootable
>> device.
>> Bochs BIOS doesn''t seems to use the offset 0x60.
>> What do you think of using cmos(0x60)?
>> Do you have some ideas?
> 
> This shouldn''t need to touch qemu at all. This is a config option
that
> should be parsed by xm/xend and passed directly off to hvmloader. Passing
it
> via hvm_info_table would make most sense in my opinion. In which case you
> need to probably pass it as an optional param to xc.hvm_build() and poke it
> into hvm_info_table from that Python C wrapper function.
> 
Thank you very much. It looks good.
I''ll try it.
> If not specified, should you keep default behaviour and try to load all
> option ROMs? I''m not fussed - it''s just a thought.
It depends on bios implimentation, I think.
BIOS on one server box can select bootable device.
BIOS on another box detects some device installed only paticular slots as
bootable.
There may be a BIOS loding all option ROM.
With avobe your idea, I want to think a little bits more.
I want to load option ROMs with a order like BCV priority.

Best Regards,

Akio Takebe

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