[Mesa-dev] llvmpipe not supporting EGL_EXT_image_dma_buf_import ?

Michel Dänzer michel at daenzer.net
Fri Oct 29 09:35:29 UTC 2021

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

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