For export this is handled through the use of the udmabuf driver to
allocate a dmabuf we can control from userspace. For import this is
handled through mmap-ing a dmabuf handle. Please note that you can
only mmap a dmabuf handle if its linear and the dmabuf handle was
created with matching read and write permissions.
Co-authored-by: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27805>
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