DRM_*MEMORYBARRIER we had were related to an MMIO space. This means
arch-specific code on the BSDs, unfortunately. Also add
DRM_MEMORYBARRIER() and change the DRM_READMEMORYBARRIER()s that used
to be read/write barriers to it.
DRM(write_string). This is the first part of removing much of the
support code for gamma from the BSD DRM, since it appears that no new
drivers are using it and nobody has ever shown interest in gamma on
BSD.
post-drm-filp-0-1-branch world. The filp is a void * cast from the
current pid. This is a temporary solution which maintains the status
quo until a proper solution is implemented.
What is really needed is a unique pointer per open, hopefully with a device
private area. This can be done in FreeBSD for all entry points except
mmap, but is difficult (sys/dev/streams/streams.c is an example). I
have partially completed code for this but have not had time to debug,
so this is a temporary fix.
