On 01/04/2022 13.39, Toke Høiland-Jørgensen wrote:
Kal Cutter Conley <kal.conley@xxxxxxxxxxx> writes:Hi, We are very interested in receiving jumbo frames (> 8000 bytes) over AF_XDP. Does XDP multi-buffer support XDP_REDIRECT with AF_XDP? What about in zero-copy mode? Cheers, KalLooking into this more I found this comment in the mlx5 driver: /* Don't enable multi buffer on XDP_REDIRECT SQ, as it's not yet * supported by upstream, and there is no defined trigger to allow * transmitting redirected multi-buffer frames. */ So at least mlx5 does not yet support XDP multi-buffer with XDP_REDIRECT. What "upstream" support is required to get XDP_REDIRECT to work with XSKs?Well, the initial patch set for multibuf explicitly blocked XDP_REDIRECT between interfaces, which is what that comment is referring to (the TX side). For AF_XDP we'd also need to define the UAPI, and maybe add a socket flag so the userspace program can signal to the kernel that it understands it? Not sure about the details. You're definitely not the only person who wants this, though; adding in some people who may have a better idea of the exact steps needed.
Cc. Eric Sage, as he also expressed interest in implementing this... --Jesper