> >>>>> "Jon" == Jon M Taylor <taylorj@ecs.csus.edu> writes:
>
> Jon> On 13 Aug 1998, Jes Sorensen wrote:
> >> No in user space - fbdev may use accel for things that can speed
> >> up the console code, like recangular blitting and clearing, it does
> >> not intend to provide some generic kernel accel API.
>
> Jon> But is has in fact done so, by allowing for driver-specific
> Jon> ioctls. That is one thing those ioctls be be used for.
>
> Its possible, but it was not the intention.
Nevertheless, it should work OK. kgicon drivers will implement
KGI acceleration ioctls as fbcon ioctls, and the LibGGI fbdev display
target will know how to use those ioctls for acceleration.
> >> When you want to have accel control in user space, you tell fbdev
> >> and it wont use acceleration for the console until the user space
> >> program finishes with it.
>
> Jon> I assume by "user space" you mean X primarily.
>
> Or something like libGGI.
LibGGI does not do any direct hardware access. Or did I
misunderstand you?
> >> We did not do that on purpose, ioctl == context switch and we
> >> don't want that.
>
> Jon> direct userspace access to accel registers == unsafe. *I*
> Jon> don't want *that*. You can get quite acceptable speed out of
> Jon> ioctls. Not the most speed possible, but in most cases that
> Jon> isn't a concern.
>
> Sorry, tough.
Well, you already gave us the tool we need to do this.
> If you want to run X on broken hardware then you'll have to take the
> risk.
Not really. All I need to do is use fbcon with a kgicon
accelerated driver, and then run XGGI using the fbdev display target.
Should work just fine.
> A context switch is not acceptable here and much worse, it will
> require you to implement a zillion drivers for acceleration of various
> chipsets which will lead to unnecessary code bloat.
The drivers are already implemented - they are the KGI drivers.
Through kgicon, I can use them with fbcon. No one else needs to care
about those acceleration ioctls if they do not want to, and yet they can
be used by usersapce code that knows about them. Best of both worlds.
Jon
--- 'Cloning and the reprogramming of DNA is the first serious step in becoming one with God.' - Scientist G. Richard Seed
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