[Mesa-dev] llvmpipe not supporting EGL_EXT_image_dma_buf_import ?

[Christian König]

Am 29.10.21 um 11:35 schrieb Michel Dänzer:
> 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)

Yeah, I'm not very keen of that either.

But for testing I think it would still be nice to have the ability to 
share DMA-bufs with software rendereres even if it is horrible slow.

Christian.