From: Lorenzo Bianconi <lore...@kernel.org> Date: Sat, 21 Sep 2024 18:52:56 +0200
> This series introduces the xdp_rx_meta struct in the xdp_buff/xdp_frame &xdp_buff is on the stack. &xdp_frame consumes headroom. IOW they're size-sensitive and putting metadata directly there might play bad; if not now, then later. Our idea (me + Toke) was as follows: - new BPF kfunc to build generic meta. If called, the driver builds a generic meta with hash, csum etc., in the data_meta area. Yes, this also consumes headroom, but only when the corresponding func is called. Introducing new fields like you're doing will consume it unconditionally; - when &xdp_frame gets converted to sk_buff, the function checks whether data_meta contains a generic structure filled with hints. We also thought about &skb_shared_info, but it's also size-sensitive as it consumes tailroom. > one as a container to store the already supported xdp rx hw hints (rx_hash > and rx_vlan, rx_timestamp will be stored in skb_shared_info area) when the > eBPF program running on the nic performs XDP_REDIRECT. Doing so, we are able > to set the skb metadata converting the xdp_buff/xdp_frame to a skb. Thanks, Olek
