[SeaBIOS] [Qemu-devel] KVM call agenda for 2013-05-28

[Laszlo Ersek]

On 05/30/13 18:57, Jordan Justen wrote:
> On Thu, May 30, 2013 at 9:41 AM, Laszlo Ersek <lersek at redhat.com> wrote:
>> On 05/30/13 18:20, Jordan Justen wrote:
>>> I think ACPI table generation lives in firmware on real products,
>>> because on real products the firmware is the point that best
>>> understands the actual hardware layout for the machine. In qemu, I
>>> would say that qemu best knows the hardware layout, given that the
>>> firmware is generally a slightly separate project from qemu.
>>>
>>> I don't think adding a coreboot layer into the picture helps, if it
>>> brings along the coreboot payload boot interface as a requirement.
>>>
>>> Then again, I don't really understand how firmware could be swapped
>>> out in this case. What would -bios do? How would the coreboot ACPI
>>> shim layer be specified to qemu?
>>
>> I guess -bios would load coreboot. Coreboot would siphon the data
>> necessary for ACPI table building through the current (same) fw_cfg
>> bottleneck, build the tables, load the boot firmware (SeaBIOS or OVMF or
>> something else -- not sure how to configure that), and pass down the
>> tables to the firmware (through a now unspecified interface -- perhaps
>> the tables could even be installed at this point). This could introduce
>> another interface (fw_cfg+something rather than just fw_cfg), but ACPI
>> table preparation would be concentrated in one project.
>>
>> I guess.
> 
> For reference, I believe that both Xen and virtualbox build ACPI table
> in the VMM rather than firmware. They both dump the tables into the
> 0xe000 segment (yuck) where firmware finds and publishes it to the OS.
> I think fw-cfg would be a reasonable alternative to this for
> communicating the tables.

I think Xen uses a separate utility called "hvmloader" that runs in the
domU.

- http://thread.gmane.org/gmane.comp.bios.coreboot.seabios/5453/focus=5668
- http://xenbits.xen.org/gitweb/?p=xen.git;a=tree;f=tools/firmware/hvmloader
- http://thread.gmane.org/gmane.comp.bios.coreboot.seabios/6255/focus=110562

Laszlo