f95f0f95cf
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. V2: nitpick: deduct -> deduce Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/158945334261.97035.555255657490688547.stgit@firesoul
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.