via k8m890 very slow with vesa

Alex Deucher alexdeucher at
Thu Nov 23 21:35:22 PST 2006

On 11/23/06, Henrik Lundberg <henrik at> wrote:
> Hi.
> I am having the exact same problem. vesa is terribly slow when moving
> windows or window contents.
> (Though, reasonably fast at drawing new content.)
> Since it seems to be stuff that should be 2D accelerated that is slow I
> thaught maybe 2D acceleration was disabled. Obviously, without 2D
> acceleration there must be some software fallback in place, which leads
> me to yet another thing I don't understand. I'm sitting here with a
> modern integrated graphics chip somewhat tightly coupled with a 2GHz
> Athlon 64 which hits the roof when I'm dragging around half a million
> pixels. Shouldn't that be fast? The software fallback doesn't seem very
> optimized OR there's a bug somwhere between just behind my eyeballs and
> .

The vesa driver is not accelerated as vesa does not provide any
interface for acceleration.  Basically vesa just provides a generic
bios interface for setting modes.  MMIO access to the FB is slow.
That is the limiting factor in performance.


> Lets go with the latter theory. According to my logs vesa and XAA loads
> fine and I see nothing else suspicious and related to this problem.
> Like you, I have ShadowFB enabled. (default and good for performance
> says a man.)
> Unlike you, I have Backing store enabled. (I honestly don't know what it
> is but I didn't notice any difference enabling it.)
> I also tried drivers from viaarena, and
>, but with no luck in any case.
> I hope someone with a solution sends it to this list.
> Best regards,
> /Henrik
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