| Re: [AD] Problems (bugs?) with video memory |
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On Sat, Sep 07, 2002 at 02:40:08PM +0200, Lo'oRiS il Kabukimono wrote:
> I notice strange behaviours on allocating video memory.
>
> Under X (windowed or not) i can allocate *any* virtual screen size, even
> more than the amount of video memory i have, and gfx_driver->vid_mem
> will report *that* amount.
IIRC under X allegro emulates the video memory with a memory bitmap,
which is copied to the real window when there's a change, this may
explain why you can get any virtual screen size.
> Under DGA2 the only option i have is a 1024x768 phisical with 1024x1279
> virtual, for a total of 2558k vram... Too few! Why?
DGA2 clearly uses the real vram, but maybe X doesn't allow this driver
to reclaim it all. Also, I think running the desktop in one or another
resolution can give you more/less for your program.
> Using FrameBuffer instead, will give me *exactly* 640x480 phisical with
> 640x13104 virtual, for a total of 16380k vram, that is the total amount
> of memory my video card have. But it can't be all free memory, since
> there are other apps running, such as X, that i suppose they use vram...
This is one of the things linux seems to do better over windows, and that
is that each graphic driver knows when their surfaces are lost and can
recover them. Other than that, the only explanation is magic... black
magic.