Re: About VBE double buffering

[Colin D Bennett]

On Wed, 10 Sep 2008 08:24:21 +0800
"y.volta" <address@hidden> wrote:

> 
>     I noticed that `grub_vbe_bios_set_display_start () which used
> AX=4F07h INT10h' used in the fancy menu patch. This will use the
> video buffer to do buffering, but this function will fail on some
> system, Collin told us in his Journal:
> 
> "However, VMware doesn't seem to support the VBE set display start
> operation, at least in the video mode that GRUB uses (for the basic
> video test, which uses indexed color 1024x768 mode). "
> 
>     so, this may have compatible issue. i think, is there any
> possible, use a non-video-card memory to be the drawing buffer, when
> done, we copy its contents to video memory? this obviously has
> performance issue, but has more compatible.

Hi,

Actually I have implemented the behavior you describe.  It is called
the 'blit' double buffering strategy, as opposed to the 'page flipping'
strategy that simply changes the display start address.

The gfxmenu detects whether page flipping is supported, and whether
there is enough video memory.  If not, then the blit method is used.

Regards,
Colin

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