On Mon, Jun 21, 2021 at 03:02:10PM +0200, Greg KH wrote:
On Mon, Jun 21, 2021 at 02:28:48PM +0200, Daniel Vetter wrote:
Also I'm wondering which is the other driver that we share buffers with. The gaudi stuff doesn't have real struct pages as backing storage, it only fills out the dma_addr_t. That tends to blow up with other drivers, and the only place where this is guaranteed to work is if you have a dynamic importer which sets the allow_peer2peer flag. Adding maintainers from other subsystems who might want to chime in here. So even aside of the big question as-is this is broken.
From what I can tell this driver is sending the buffers to other instances of the same hardware,
A dmabuf is consumed by something else in the kernel calling dma_buf_map_attachment() on the FD.
What is the other side of this? I don't see any dma_buf_map_attachment() calls in drivers/misc, or added in this patch set.
AFAIK the only viable in-tree other side is in mlx5 (look in umem_dmabuf.c)
Though as we already talked habana has their own networking (out of tree, presumably) so I suspect this is really to support some out of tree stuff??
Jason