Re: Should linuxkpi linux_file_ioctl support flexible array copy?

Hi,
Thanks for the questions!


On Sat, Feb 14, 2026 at 11:20:58PM +0000, Bjoern A. Zeeb wrote:
>
> Let me ask two totally different questions:
>
> (a) is this udmabuf or u-dma-buf?

It is the mainline linux udmabuf driver
(linux/drivers/dma-buf/udmabuf.c)


> (b) what are the expected consumers for your code?

The primary consumer is QEMU. When passing the `-device
virtio-gpu-pci,blob=true` parameter to launch QEMU, it allows the host
compositor to import the DMA-BUF directly (zero-copy), instead of having
to do an explicit GPU upload when using shared memory (shm).

It is a project I see in the SummerOfCodeIdeas page. Details are in
https://wiki.freebsd.org/SummerOfCodeIdeas#Port_or_reimplement_udmabuf

Best regards,
Zishun Yi