Re: About VBE double buffering

[Vesa Jääskeläinen]

y.volta 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.

It will have backwards compatibility mode if not available. And before I
will commit any change to support hardware double buffering I will make
sure it works in qemu/vmware/my hardware so do not worry about that one.

>     Furthmore, i suggest, we should implement the bank-switch function in VBE 
> framework, for there are a few system's video card may have no LFB modes. for 
> example, here is a card i meet: ( i gathered 22 cards, it is only one without 
> lfb in each modes; many cards have no lfb in 4 colours mode. )

As I said previously, I have no plan to work with bank switch
functionality. You are however free to do so.

And please state what card you had?

I am pretty surprised that you got vbe3.0 there and no LFB.

Oh... and I pretty much don't care about 4 color modes ;). In my opinion
they shall be unsupported. 256 index color in minimum feasible for any use.