Hi,
The idea is to create a GEM bo in one process and pass the prime handle of the it to another process, which in turn uses the handle only to map and write. This could be useful for Chrome OS architecture, where the Web content ("unpriviledged process") maps and CPU-draws a buffer, which was previously allocated in the GPU process ("priviledged process").
In v2, I've added a patch that Daniel kindly drafted to allow the unpriviledged process flush through a prime fd. In v3, I've fixed a few concerns and then added end_cpu_access to i915.
To validate all this I'm using igt, and sending the tests for review now. Please take a look.
Tiago
Daniel Thompson (1): drm: prime: Honour O_RDWR during prime-handle-to-fd
Daniel Vetter (1): dma-buf: Add ioctls to allow userspace to flush
Tiago Vignatti (2): drm/i915: Implement end_cpu_access drm/i915: Use CPU mapping for userspace dma-buf mmap()
drivers/dma-buf/dma-buf.c | 47 ++++++++++++++++++++++++++++++++++ drivers/gpu/drm/drm_prime.c | 10 +++----- drivers/gpu/drm/i915/i915_gem_dmabuf.c | 28 +++++++++++++++++++- include/uapi/drm/drm.h | 1 + include/uapi/linux/dma-buf.h | 39 ++++++++++++++++++++++++++++ 5 files changed, 117 insertions(+), 8 deletions(-) create mode 100644 include/uapi/linux/dma-buf.h