> >>>>> "Jon" == Jon M Taylor <taylorj@ecs.csus.edu> writes:
>
> Jon> On Wed, 12 Aug 1998, Geert Uytterhoeven wrote:
> >> Fbcon doesn't export rectangular blitting neither. fb.h may suggest
> >> so, but that was preliminary. Just removed it in cvs.
>
> Jon> Huh. OK, so all accels now are to be done with
> Jon> driver-specific ioctls?
>
> 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.
But is has in fact done so, by allowing for driver-specific
ioctls. That is one thing those ioctls be be used for.
> 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.
I assume by "user space" you mean X primarily.
> >> Driver specific MMIO mmap, I assume?
>
> Jon> Or ioctls. I tend to favor ioctls, because giving userspace
> Jon> direct access to the MMIO registers still leaves open the
> Jon> prossibility of crashes. Not all combinations of register writes
> Jon> are guaranteed legal.
>
> We did not do that on purpose, ioctl == context switch and we don't
> want that.
direct userspace access to accel registers == unsafe. *I* don't
want *that*. You can get quite acceptable speed out of ioctls. Not the
most speed possible, but in most cases that isn't a concern.
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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