From 7f3a4257159dea8e7ef66d1a539dc6df708b8ed3 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 7 Aug 2024 15:17:46 +0200 Subject: Adding upstream version 6.10.3. Signed-off-by: Daniel Baumann --- Documentation/networking/xsk-tx-metadata.rst | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'Documentation/networking/xsk-tx-metadata.rst') 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 -- cgit v1.2.3