Re: [Bochs-developers] [Qemu-devel] [PATCH 0/3] Add BIOS splash image support

[Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>]

On 17.12.2008 14:09, Laurent Vivier wrote:
> Le mercredi 17 décembre 2008 à 01:10 +0100, Carl-Daniel Hailfinger a
> écrit :
>   
>> On 16.12.2008 22:51, Laurent Vivier wrote:
>>     
>>> Le mardi 16 décembre 2008 à 22:46 +0200, Blue Swirl a écrit :
>>>   
>>>       
>>>> On 12/16/08, Anthony Liguori <anthony@codemonkey.ws> wrote:
>>>>     
>>>>         
>>>>> Blue Swirl wrote:
>>>>>       
>>>>>           
>>>   
>>>       
>>>>>>  The control channel may still be needed.
>>>>>>
>>>>>> Alternatively the BIOS could load the image and fade parameters from a
>>>>>> new ROM or from the configuration device and draw it to screen. This
>>>>>> would need some PNG support to BIOS, or that the image stored in raw
>>>>>> form.
>>>>>>
>>>>>>
>>>>>>         
>>>>>>             
>>>>>  Yeah, having QEMU render to the VGA directly is a bit ugly.  It would be
>>>>> nicer if the BIOS actually rendered the image but I'm not sure I think we
>>>>> should reject the patch just because it doesn't.
>>>>>       
>>>>>           
>>>> Actually this way the image can be in full color even if the emulated
>>>> device was an EGA in text mode.
>>>>     
>>>>         
>>> And you can provide the image name on the command line, and complexity
>>> is in Qemu, not in BIOS.
>>>   
>>>       
>> If one of the goals of QEMU is to be somewhat similar to hardware, this
>> should be done in the BIOS.
>>     
>
> A lot of things in Qemu are already not similar to hardware: virtio,
> firmware configuration device, instruction timing...
>
>   
>> What happens if the BIOS provides a splash screen? Will it override the
>> QEMU splash screen?
>>     
>
> Yes. The BIOS asks Qemu to display the image... or not.
>   

What happens if you run a native BIOS/EFI/whatever for the hardware
emulated in QEMU? Some people try to do exactly that.


>>> But in fact, my first idea was to read the image data from the
>>> configuration device (which is always possible with LOGO_CMD_OFFSET),
>>> but when I saw how it has been done in VirtualBox, I though it was a
>>> good idea.
>>>   
>>>       
>> Modern x86 BIOSes read the splash screen from the BIOS ROM and the
>> settings from NVRAM (sometimes the BIOS ROM is used for that as well by
>> reflashing a sector of the ROM on every boot).
>>     
>
> A BIOS, by definition, is not modern... ;-)
>   

Agreed.


> (Openfirmware is...)
>   

Even EFI is more modern than OpenFirmware. However, the most important
question here is how you quantify modernness ;-)

Speaking as a coreboot (really modern x86 firmware) developer, I'd like
to keep the number of workarounds for QEMU hardware quirks to a minimum.

Regards,
Carl-Daniel

-- 
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