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

[Keith Whitwell <keith@tungstengraphics.com>]

Christoph Hellwig wrote:
> On Wed, Sep 29, 2004 at 02:29:24PM +0100, Keith Whitwell wrote:
> 
>>Christoph Hellwig wrote:
>>
>>
>>> - drm_flush is a noop.  a NULL ->flush does the same thing, just easier
>>> - dito or ->poll
>>> - dito for ->read
>>
>>Pretty sure you couldn't get away with null for these in 2.4, at least.
> 
> 
> Umm, of course you could.  There's only a hanfull instance defining a
> ->flush at all.  Similarly all file_ops for regular files and many char
> devices don't have ->poll.  no ->read is pretty rare but 2.4 chæcks it
> aswell.

I tried it, led to crashes (panics, I guess) & the change had to be reverted. 
  On reverting the crashes stopped.  This was for poll and read:

revision 1.12
date: 2003-04-23 23:42:28 +0000;  author: keithw;  state: Exp;  lines: +13 -0
Install dummy/noop read & poll fops unless the driver has replacements.
----------------------------
revision 1.11
date: 2003-04-22 08:06:13 +0000;  author: keithw;  state: Exp;  lines: +0 -94
remove DRM read, poll and write_string


I didn't do any more investigation & the behaviour may well be different 
nowadays.

Keith