This series originated from the request from Paul, "can you enable page faults"? After some though and discussion, we came up with 3 debug features to implement: 1. echo 1 > /sys/kernel/debug/dri/0/i915_debug_flags Make all scratch pages fault on access 2. echo 2 > /sys/kernel/debug/dri/0/i915_debug_flags Unbind all buffers synchronously, so any batch which has bad code will fault every time and not get lucky by hitting a buffer it bound. This will not catch cases where it accidentally reads/writes someone else's buffer. 3. echo 4 > /sys/kernel/debug/dri/0/i915_debug_flags Add an extra page to all user allocated objects which will fault when accessed. This is meant to catch the case where mesa overruns one of it's local buffers. It's meant to be a finer grained version of #1, and was a specific request. Personally, I don't know how useful page faults are. The one time I tried to turn it on previously, I remember getting a hard hang, but my memory if very fuzzy. Putt this out there for review, and hopefully for Paul to test as soon as he has something read. Ben Widawsky (6): drm/i915: Faults for scratch PTEs drm/i915: Debugfs for setting debug_flags drm/i915: Reset scratch pages when using debug_flags drm/i915: Synchronous execbuf for debug drm/i915: Let userspace create a faultable pad page drm/i915: distinguish pad and fault pages drivers/gpu/drm/i915/i915_debugfs.c | 53 +++++++++++++++++++ drivers/gpu/drm/i915/i915_drv.c | 3 ++ drivers/gpu/drm/i915/i915_drv.h | 17 +++++-- drivers/gpu/drm/i915/i915_gem.c | 7 +++ drivers/gpu/drm/i915/i915_gem_execbuffer.c | 7 ++- drivers/gpu/drm/i915/i915_gem_gtt.c | 81 +++++++++++++++++++++++++----- 6 files changed, 151 insertions(+), 17 deletions(-) -- 1.8.3.1
