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When userland detected that this ioctl was supported (by version number check), it used it in a racy way -- dispatch delayed swap, wait for vblank, continue rendering. As there was no mechanism for it to wait for the swap to finish, sometimes it would render before the swap and garbage would be displayed on the screen. By removing the ioctl and returning -EINVAL, userland returns to its previous, correct rendering path of waiting for a vblank then dispatching a swap. The only path that could have used this ioctl correctly was page flipping, which relied on only one client running and emitting wait-for-vblank-before-rendering in the command stream. That path also falls back correctly, at the performance cost of not being able to queue up rendering before the flip occurs. Signed-off-by: Eric Anholt <eric@anholt.net> Signed-off-by: Dave Airlie <airlied@linux.ie> |
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|---|---|---|
| .. | ||
| i810 | ||
| i830 | ||
| i915 | ||
| mga | ||
| r128 | ||
| radeon | ||
| savage | ||
| sis | ||
| tdfx | ||
| via | ||
| ati_pcigart.c | ||
| drm_agpsupport.c | ||
| drm_auth.c | ||
| drm_bufs.c | ||
| drm_cache.c | ||
| drm_context.c | ||
| drm_dma.c | ||
| drm_drawable.c | ||
| drm_drv.c | ||
| drm_fops.c | ||
| drm_gem.c | ||
| drm_hashtab.c | ||
| drm_ioc32.c | ||
| drm_ioctl.c | ||
| drm_irq.c | ||
| drm_lock.c | ||
| drm_memory.c | ||
| drm_mm.c | ||
| drm_pci.c | ||
| drm_proc.c | ||
| drm_scatter.c | ||
| drm_sman.c | ||
| drm_stub.c | ||
| drm_sysfs.c | ||
| drm_vm.c | ||
| Kconfig | ||
| Makefile | ||
| README.drm | ||
************************************************************
* 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