[SeaBIOS] [PATCH 2/3] bochsvga: Implement vbe 15h function

Hiroshi Miura miurahr at linux.com
Wed Sep 19 02:06:18 CEST 2012

On 2012年09月18日 14:56, Gerd Hoffmann wrote:
>   Hi,
>>> Out of curiousity, though, why not populate the edid block at init?
>>> Something like:
>> I think we need runtime generation of EDID when supporting following cases;
>> (a) terminal service
>> -Assume  that we use qemu-kvm and seabios/vgabios for Terminal service, (as same as Windows Server).
>> -Thin client that run VNC client connect.
>> -qemu may want to ask guest that new (virtual) display is connected and update its resolution.
>>   --qemu may trigger guest OS as if your note-PC triggered when connecting projector.
>>   --Guest OS request EDID of new (virtual) display
>>   -- seabios/vgabios ask qemu about preferable resolution.
>>   -- seabios/vgabios return EDID that offer resolution that is good for client.
>> (b) vnc client resolution change
>> - vnc client change its resolution.
>> - qemu may ask guest OS refresh its resolution.
>> - Seabios/vgabios report a preferred resolution as EDID.
>> If we don't need such feature (in future), populating the edid block at init is ok.
> I think we should populate at init time.
> BTW: a CONFIG_EDID would be nice.

I'd like to rework it (now doing...) to pupulation at init time.

>> As Gred suggest me, we can add bochs api that offer preferable resolution, and use it for
>> above scenario, that may be  great.
> Indeed ...
>> I'm sorry I don't know how trigger guest os from host  when VNC client connect
>> or change its resolution.
> ... but seabios doesn't need to worry about this.
> The usual way the (virtual) hardware signals such changes to the os is
> to raise an interrupt, and the os gfx card driver handles it.  No
> seabios involved here.  Even if seabios would handle the interrupt and
> update the edid there would still be the problem that there simply is no
> bios interface which seabios could use to inform the guest os.
> sea(vga)bios should just use what it finds at boot time and not worry
> about any changes while the guest is running.  If something changes
> seabios will pick it up on the next reboot.

Thanks for clarification.


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