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Date:   Tue, 17 Mar 2020 13:42:43 -0700
From:   Jakub Kicinski <>
To:     Jesper Dangaard Brouer <>
        Toke Høiland-Jørgensen <>,
        Daniel Borkmann <>,
        Alexei Starovoitov <>,
        John Fastabend <>,
        Alexander Duyck <>,
        Jeff Kirsher <>,
        David Ahern <>,
        Willem de Bruijn <>,
        Ilias Apalodimas <>,
        Lorenzo Bianconi <>
Subject: Re: [PATCH RFC v1 01/15] xdp: add frame size to xdp_buff

On Tue, 17 Mar 2020 18:29:12 +0100 Jesper Dangaard Brouer wrote:
> XDP have evolved to support several frame sizes, but xdp_buff was not
> updated with this information. The frame size (frame_sz) member of
> xdp_buff is introduced to know the real size of the memory the frame is
> delivered in.
> When introducing this also make it clear that some tailroom is
> reserved/required when creating SKBs using build_skb().
> It would also have been an option to introduce a pointer to
> data_hard_end (with reserved offset). The advantage with frame_sz is
> that (like rxq) drivers only need to setup/assign this value once per
> NAPI cycle. Due to XDP-generic (and some drivers) it's not possible to
> store frame_sz inside xdp_rxq_info, because it's varies per packet as it
> can be based/depend on packet length.

Do you reckon it would be too ugly to make xdp-generic suffer and have
it set the length in rxq per packet? We shouldn't handle multiple
packets from the same rxq in parallel, no?

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