Re: About VBE double buffering

["Vesa Jääskeläinen" <chaac@nic.fi>]

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.