Re: New DRM driver model - gets rid of DRM() macros!

[Keith Whitwell <keith@tungstengraphics.com>]

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...

Keith