On 2021-10-28 14:02, Christian König wrote: > Well I'm not an expert on llvmpipe, but as far as I know that's a general > problem. > > DMA-buf is used by the Linux kernel drivers to pass hardware bufefrs between > processes and drivers. > > Since llvmpipe as a software renderer it has no kernel driver, so there is no > easy way to implement that.
Even if there was, CPU reads from dma-bufs imported from a HW driver may be extremely slow, so they should be avoided other than for specific setups where they're known to be guaranteed to perform adequately. (This performance trap is why I think allowing mmap for dma-buf fds was a mistake) -- Earthling Michel Dänzer | https://redhat.com Libre software enthusiast | Mesa and Xwayland developer
