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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-08-07 13:18:06 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-08-07 13:18:06 +0000 |
commit | 638a9e433ecd61e64761352dbec1fa4f5874c941 (patch) | |
tree | fdbff74a238d7a5a7d1cef071b7230bc064b9f25 /Documentation/networking/xsk-tx-metadata.rst | |
parent | Releasing progress-linux version 6.9.12-1~progress7.99u1. (diff) | |
download | linux-638a9e433ecd61e64761352dbec1fa4f5874c941.tar.xz linux-638a9e433ecd61e64761352dbec1fa4f5874c941.zip |
Merging upstream version 6.10.3.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'Documentation/networking/xsk-tx-metadata.rst')
-rw-r--r-- | Documentation/networking/xsk-tx-metadata.rst | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/Documentation/networking/xsk-tx-metadata.rst b/Documentation/networking/xsk-tx-metadata.rst index bd033fe95c..e76b0cfc32 100644 --- a/Documentation/networking/xsk-tx-metadata.rst +++ b/Documentation/networking/xsk-tx-metadata.rst @@ -11,12 +11,16 @@ metadata on the receive side. General Design ============== -The headroom for the metadata is reserved via ``tx_metadata_len`` in -``struct xdp_umem_reg``. The metadata length is therefore the same for -every socket that shares the same umem. The metadata layout is a fixed UAPI, -refer to ``union xsk_tx_metadata`` in ``include/uapi/linux/if_xdp.h``. -Thus, generally, the ``tx_metadata_len`` field above should contain -``sizeof(union xsk_tx_metadata)``. +The headroom for the metadata is reserved via ``tx_metadata_len`` and +``XDP_UMEM_TX_METADATA_LEN`` flag in ``struct xdp_umem_reg``. The metadata +length is therefore the same for every socket that shares the same umem. +The metadata layout is a fixed UAPI, refer to ``union xsk_tx_metadata`` in +``include/uapi/linux/if_xdp.h``. Thus, generally, the ``tx_metadata_len`` +field above should contain ``sizeof(union xsk_tx_metadata)``. + +Note that in the original implementation the ``XDP_UMEM_TX_METADATA_LEN`` +flag was not required. Applications might attempt to create a umem +with a flag first and if it fails, do another attempt without a flag. The headroom and the metadata itself should be located right before ``xdp_desc->addr`` in the umem frame. Within a frame, the metadata |