To get the fun stuff out of the way, the legacy hws is allocated by
userspace when the gpu needs a gfx hws. And there's no reference-counting
going on, so userspace can simply screw everyone over.
At least it's not as horrible as i810, where the ringbuffer is allocated
by userspace ...
We can't fix this disaster, but we can at least tidy up the code a
bit to make things clearer:
- Drop the drm ioremap indirection.
- Add a new new read_legacy_status_page to paper over the differences
between the legacy gfx hws and the physical hws shared with the
new ringbuffer code.
- Add a pointer in dev_priv->dri1 for the cpu addresses - that one is
an iomem remapping as opposed to all other hw status pages. This is
just prep work to make sparse happy.
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
************************************************************
* For the very latest on DRI development, please see: *
* http://dri.freedesktop.org/ *
************************************************************
The Direct Rendering Manager (drm) is a device-independent kernel-level
device driver that provides support for the XFree86 Direct Rendering
Infrastructure (DRI).
The DRM supports the Direct Rendering Infrastructure (DRI) in four major
ways:
1. The DRM provides synchronized access to the graphics hardware via
the use of an optimized two-tiered lock.
2. The DRM enforces the DRI security policy for access to the graphics
hardware by only allowing authenticated X11 clients access to
restricted regions of memory.
3. The DRM provides a generic DMA engine, complete with multiple
queues and the ability to detect the need for an OpenGL context
switch.
4. The DRM is extensible via the use of small device-specific modules
that rely extensively on the API exported by the DRM module.
Documentation on the DRI is available from:
http://dri.freedesktop.org/wiki/Documentation
http://sourceforge.net/project/showfiles.php?group_id=387
http://dri.sourceforge.net/doc/
For specific information about kernel-level support, see:
The Direct Rendering Manager, Kernel Support for the Direct Rendering
Infrastructure
http://dri.sourceforge.net/doc/drm_low_level.html
Hardware Locking for the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/hardware_locking_low_level.html
A Security Analysis of the Direct Rendering Infrastructure
http://dri.sourceforge.net/doc/security_low_level.html
316d388450