On Mon, May 06, 2019 at 04:20:34PM +0200, Gerd Hoffmann wrote:
On Mon, May 06, 2019 at 03:09:20PM +0200, Thomas Zimmermann wrote:
Hi
Am 06.05.19 um 14:22 schrieb Gerd Hoffmann:
GEM VRAM could implement PRIME helpers, which would allow for using the generic fbcon.
bochs_gem_prime_*() functions with this series applied look like you can just rename them & move over to vram helpers.
It's not a full prime implementation, specifically actual export/import isn't there. But pin+vmap (needed by generic fbcon) is implemented.
I did have a patch to do this, but then I read that prime requires DMA for buffer sharing and bochs works only because it's emulated.
For actual buffer sharing with other drivers yes because dma-bufs typically are a bunch of pages (struct page**) and live in RAM.
Not sure whenever it is possible or useful to place the vram in ZONE_DEVICE to get page structs for it, then export buffers located in vram that way without copying them over to main memory. I suspect most importers would fail to properly setup PCI-PCI dma in that case.
Christian König is working on p2p dma-buf sharing. Not sure that's worth it for virtual devices, but could be fun to wire up I guess. -Daniel
If bochs' implementation is complete enough to be useful for other drivers, I'll add it to the patch set.
It's good enough for generic fbcon.
cheers, Gerd