VGA Arbiter

Keith Packard keithp at
Fri Oct 26 19:39:09 PDT 2007

On Sat, 2007-10-27 at 11:35 +1000, Benjamin Herrenschmidt wrote:

> The interface was something I quickly threw together, it doesn't
> necessarily have to be that way. In fact, I wonder if a sysfs file might
> be better. Anyway, it's good to have a proof of concept to work from.

Does this have to be visible from user mode at all? With kernel mode
modesetting and graphics access, would it not be better to just provide
this as a library to the internal graphics drivers and avoid exposing it
to user mode?

> This is important because you cannot reliably use interrupts for
> example, like the DRM does on these, if your MMIO decoding can be
> switched off by another cards driver trying to get to its own legacy IOs
> or memory space.

With the arbitrartion handled from within the kernel, I'm wondering if
we can't make even interrupts work...

keith.packard at
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