On 21/10/15 16:24, Chris Wilson wrote:
Our GPUs impose certain requirements upon buffers that depend upon how
exactly they are used. Typically this is expressed as that they require
a larger surface than would be naively computed by pitch * height.
Normally such requirements are hidden away in the userspace driver, but
when we accept pointers from strangers and later impose extra conditions
on them, the original client allocator has no idea about the
monstrosities in the GPU and we require the userspace driver to inform
the kernel how many padding pages are required beyond the client
allocation.
v2: Long time, no see
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
As mentioned by Chris, IGT can be found as "tests/gem_exec_pad_to_size:
Test object padding at execbuf", might need a respin for top-down
allocation policy change.
And libdrm support is "libdrm_intel: Add API for execbuf pad to size
functionality".
Both patches from April this year.
Regards,
Tvrtko
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