On Tue, Aug 3, 2021 at 10:10 AM Kishen Maloor [off-list ref] wrote:

This change adds userspace support for SO_TXTIME in AF_XDP
to include a specific TXTIME (aka "Launch Time")
with XDP frames issued from userspace XDP applications.

The userspace API has been expanded with two helper functons:

- int xsk_socket__enable_so_txtime(struct xsk_socket *xsk, bool enable)
   Sets the SO_TXTIME option on the AF_XDP socket (using setsockopt()).

- void xsk_umem__set_md_txtime(void *umem_area, __u64 chunkAddr,
                               __s64 txtime)
   Packages the application supplied TXTIME into struct xdp_user_tx_metadata:
   struct xdp_user_tx_metadata {
        __u64 timestamp;
        __u32 md_valid;
        __u32 btf_id;
   };
   and stores it in the XDP metadata area, which precedes the XDP frame.

Signed-off-by: Kishen Maloor <redacted>
---

Same comments as in [0] regarding the AF_XDP APIs in libbpf.

  [0] https://lore.kernel.org/bpf/CAEf4BzZ44wc-+r6o7vthddt5BoePdg0cQn83g8qkyPMAca4vvA@mail.gmail.com/ (local)

 tools/include/uapi/linux/if_xdp.h     |  2 ++
 tools/include/uapi/linux/xdp_md_std.h | 14 ++++++++++++++
 tools/lib/bpf/xsk.h                   | 27 ++++++++++++++++++++++++++-
 3 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 tools/include/uapi/linux/xdp_md_std.h

[...]