New DRM driver model - gets rid of DRM() macros!
keith at tungstengraphics.com
Wed Sep 29 07:27:12 PDT 2004
Christoph Hellwig wrote:
> On Wed, Sep 29, 2004 at 03:12:03PM +0100, Keith Whitwell wrote:
>>Thinking about it, it may not have been a problem of crashing, but rather that
>> the behaviour visible from a program attempting to read (or poll) was
>>different with noop versions of these functions to NULL versions, and that was
>>causing problems. This is 18 months ago, so yes, I'm being vague.
>>The X server does look at this file descriptor, which is where the problem
>>would have arisen, but only the gamma & maybe ffb drivers do anything with it.
> Indeed, for read you're returning 0 now instead of the -EINVAL from common
> code when no ->read is present. I'd say the current drm behaviour is a bug,
> but if X drivers rely on it.
I'd agree, but it's a widely distributed bug. I guess we can fix it in the X
server, but even better would be to rip out the code as it's fundamentally
misguided, based on a wierd idea that the kernel would somehow ask the X
server to perform a context switch between two userspace clients...
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