Re: cmpxchg is not available to generic code

[Andrew Morton <akpm@linux-foundation.org>]

On Thu, 19 Jul 2007 09:02:03 +0100 (IST) Dave Airlie <airlied@linux.ie> wrote:

> 
> 
> > arm:
> >
> > drivers/char/drm/drm_lock.c: In function `drm_lock_take':
> > drivers/char/drm/drm_lock.c:221: error: implicit declaration of function `cmpxchg'
> >
> > You might be able to use atomic_cmpxchg, which _is_ present
> > on all architectures.  Or use a spinlock.
> >
> > What's that code doing anyway?  driver-private locking primitives?
> 
> When did arm suddenly start wanting DRM?

It's selectable in config.  allmodconfig broke.

> they need to grow a userpsace 
> cmpxchg as davem mentioned to go along with this, changing the drm now 
> isn't possible due to backwards compat..

For reference purposes, that position is not acceptable.  We _never_ accept the
"oh I can't change my proposed kernel interface because I already have
userspace relying on it" argument.

Hopefully that won't be an issue here.  I guess DRM now needs a
`depends on !ARM'.