diff options
Diffstat (limited to 'src/plugins/af_xdp/device.c')
| -rw-r--r-- | src/plugins/af_xdp/device.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/src/plugins/af_xdp/device.c b/src/plugins/af_xdp/device.c index fabf85adfa6..35ba617d6e3 100644 --- a/src/plugins/af_xdp/device.c +++ b/src/plugins/af_xdp/device.c @@ -208,6 +208,18 @@ af_xdp_create_queue (vlib_main_t * vm, af_xdp_create_if_args_t * args, umem_config.comp_size = args->txq_size; umem_config.frame_size = sizeof (vlib_buffer_t) + vlib_buffer_get_default_data_size (vm); + /* + * Note about headroom: for some reasons, there seem to be a discrepency + * between 0-copy and copy mode: + * - 0-copy: XDP_PACKET_HEADROOM will be added to the user headroom + * - copy: nothing is added to the user headroom + * We privileged 0-copy and set headroom so that frame_headroom + + * XDP_PACKET_HEADROOM == sizeof(vlib_buffer_t), ie data will correctly + * point to vlib_buffer_t->data for 0-copy. In copy mode, we have to add + * XDP_PACKET_HEADROOM to desc offset during refill. + */ + STATIC_ASSERT (sizeof (vlib_buffer_t) >= XDP_PACKET_HEADROOM, "wrong size"); + umem_config.frame_headroom = sizeof (vlib_buffer_t) - XDP_PACKET_HEADROOM; umem_config.flags = XDP_UMEM_UNALIGNED_CHUNK_FLAG; if (xsk_umem__create (umem, uword_to_pointer (vm->buffer_main->buffer_mem_start, void *), |