4a9b052a59
The dpaa2-eth driver reserve some headroom used for hardware and software annotation area in RX/TX buffers. Thus, xdp.data_hard_start doesn't start at page boundary. When XDP is configured the area reserved via dpaa2_fd_get_offset(fd) is 448 bytes of which XDP have reserved 256 bytes. As frame_sz is calculated as an offset from xdp_buff.data_hard_start, an adjust from the full PAGE_SIZE == DPAA2_ETH_RX_BUF_RAW_SIZE. When doing XDP_REDIRECT, the driver doesn't need this reserved headroom any-longer and allows xdp_do_redirect() to use it. This is an advantage for the drivers own ndo-xdp_xmit, as it uses part of this headroom for itself. Patch also adjust frame_sz in this case. The driver cannot support XDP data_meta, because it uses the headroom just before xdp.data for struct dpaa2_eth_swa (DPAA2_ETH_SWA_SIZE=64), when transmitting the packet. When transmitting a xdp_frame in dpaa2_eth_xdp_xmit_frame (call via ndo_xdp_xmit) is uses this area to store a pointer to xdp_frame and dma_size, which is used in TX completion (free_tx_fd) to return frame via xdp_return_frame(). Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Ioana Radulescu <ruxandra.radulescu@nxp.com> Link: https://lore.kernel.org/bpf/158945339348.97035.8562488847066908856.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.