Re: LiveCD bootloader

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

On 09/09/10 03:33, Brendan Trotter wrote:
> Hi,
>
> On Thu, Sep 9, 2010 at 8:30 AM, Teresa e Junior<teresaejunior@gmail.com>  wrote:
>    
>> What do you mean with that? Let us suppose, I set:
>>
>> GRUB_GFXMODE=1280x800,1024x768,640x480
>>
>> and if the hardware supports the first, it will use the first, and so
>> forth?
>>      
> Not all of my previous assumptions were obsolete (and this time I
> checked the source code for GRUB2 to make sure).
>
> If the video card and software supports the first video mode then GRUB
> will use the first video mode; regardless of whether or not the
> monitor itself supports the video mode.
>    
GRUB uses VBE on real hardware (I have some intelfb code but it's not 
functional yet), in this case it's VBE responsibility to verify monitor 
capabilities. Even having EDID without knowing the card characteristics 
you can't really check it since card itself may perform 
post-transformations like stretching or splitting the image among monitors.
> This means that: for the monitors I have here; for the newest 3 (LCD)
> monitors you'll get 1280x800 and it will work fine (although probably
> a little blurry due to not using the native resolution of any of the
> monitor's); for the largest CRT you'll probably get a squashed image
> that might still be readable (within the monitors maximum frequency,
> but unsupported aspect ratio); for the next CRT you'll get a black
> screen with an error message from the on screen display; for the next
> 2 CRTs you'll get an unreadable (flickering/rolling) mess; and for the
> last monitor (a very old CRT) you'll probably cause permanent damage.
>
>
> Cheers,
>
> Brendan
>
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>
>    


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko