EFI Graphics

EFI Graphics

[Phillip Susi]

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So far I have gathered that grub uses the GOP ( Graphics Output
Protocol ) EFI interface for graphics.  Am I correct in assuming that
interface is implemented via an EFI option rom driver on the video
card, or a bios fallback?  It seems that my system is limited to a
simple text mode ( and the EFI shell could upgrade it to only a
slightly higher line count mode, didn't even get to 50 ).  Is this a
limitation of my particular interface, or the GOP protocol?  In other
words, if I had a different video card, could grub-efi possibly run
gfxmenu?
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Re: EFI Graphics

[Vladimir 'φ-coder/phcoder' Serbinenko]

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On 09.11.2011 03:11, Phillip Susi wrote:
> So far I have gathered that grub uses the GOP ( Graphics Output
> Protocol ) EFI interface for graphics.  Am I correct in assuming that
> interface is implemented via an EFI option rom driver on the video
> card, or a bios fallback?  It seems that my system is limited to a
> simple text mode ( and the EFI shell could upgrade it to only a
> slightly higher line count mode, didn't even get to 50 ).  Is this a
> limitation of my particular interface, or the GOP protocol?  In other
> words, if I had a different video card, could grub-efi possibly run
> gfxmenu?
With GOP GRUB just uses whatever EFI gives it. How it is implemented
inside EFI GRUB has no idea and no control over it. So you have to ask
EFI developpers.
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-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko



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Re: EFI Graphics

[Phillip Susi]

On 11/9/2011 3:52 AM, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
> With GOP GRUB just uses whatever EFI gives it. How it is implemented
> inside EFI GRUB has no idea and no control over it. So you have to ask
> EFI developpers.

Yes, but is EFI capable of supplying grub with graphics support or is 
the GOP interface inherently text only?

Re: EFI Graphics

[Jordan Justen]

2011/11/9 Phillip Susi <psusi@cfl.rr.com>:
> On 11/9/2011 3:52 AM, Vladimir 'φ-coder/phcoder' Serbinenko wrote:
>>
>> With GOP GRUB just uses whatever EFI gives it. How it is implemented
>> inside EFI GRUB has no idea and no control over it. So you have to ask
>> EFI developpers.
>
> Yes, but is EFI capable of supplying grub with graphics support or is the
> GOP interface inherently text only?

GOP is the GraphicsOutput protocol, so it is not text based.  There is
often a GraphicsConsole driver that will allow text to be drawn on the
screen (via GOP).

At the EFI shell, you might be able to verify GOP is present with dh.
For example:

Shell> dh -p graphicsoutput
Handle dump by protocol 'GraphicsOutput'
 71: DevPath (..0x2,0x0)/AcpiAdr(0x80010100))Txtout GraphicsOutput ConOut

Some older EFI systems may not support UEFI 2.0, which is when GOP was
added.  You might look at the output of the ver shell command.  But,
there are other reasons why GOP may not be available in the system
too.

-Jordan