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Re: Can we get video card information in EFI environment ?

From: Bean
Subject: Re: Can we get video card information in EFI environment ?
Date: Mon, 9 Jun 2008 01:35:01 +0800

On Mon, Jun 9, 2008 at 1:17 AM, Vesa Jääskeläinen <address@hidden> wrote:
> Bean wrote:
>> BTW, you need to remove the udev start script from /etc/rcS.d,
>> otherwise the screen would scramble again. I believe the cause is
>> agppart. Fame buffer of EFI is a little strange, the line length is
>> not equal to width * 4, for example, my macbook:
>> width: 1280
>> depth: 32
>> line length: 8192
> This is quite normal and can change from card to card. So thats the reason
> you ask for line length from VBE/HW.
>> So there is some invisible space after the screen boundary. But in
>> bios emulation mode, the length is exactly width * 4. I think the
>> driver should take this into account, or reconfigure the video
>> hardware to use the new line length. (Anyone know how to do it ?)
> GRUB 2 VBE driver already should work nicely with this (assuming VBE is
> available). If you are planning to do EFI driver then you just use its API
> to do blitting. Writing driver for EFI should be rather easy if I remember
> correctly its interface. Can't write that driver myself unless someone wants
> to provide me environment to do the coding.


I think the vbe driver need to call bios, is there a way to do it directly ?

EFI have uga draw protocol that can do bitblt, but they don't have a
method to query low level information like frame buffer address and
line length easily.


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