On Wed, Dec 14, 2022 at 3:46 PM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote: > > Stanislav Fomichev <sdf@xxxxxxxxxx> writes: > > > On Wed, Dec 14, 2022 at 2:34 AM Toke Høiland-Jørgensen <toke@xxxxxxxxxx> wrote: > >> > >> Stanislav Fomichev <sdf@xxxxxxxxxx> writes: > >> > >> > On Tue, Dec 13, 2022 at 8:37 AM David Vernet <void@xxxxxxxxxxxxx> wrote: > >> >> > >> >> On Mon, Dec 12, 2022 at 06:35:51PM -0800, Stanislav Fomichev wrote: > >> >> > Document all current use-cases and assumptions. > >> >> > > >> >> > Cc: John Fastabend <john.fastabend@xxxxxxxxx> > >> >> > Cc: David Ahern <dsahern@xxxxxxxxx> > >> >> > Cc: Martin KaFai Lau <martin.lau@xxxxxxxxx> > >> >> > Cc: Jakub Kicinski <kuba@xxxxxxxxxx> > >> >> > Cc: Willem de Bruijn <willemb@xxxxxxxxxx> > >> >> > Cc: Jesper Dangaard Brouer <brouer@xxxxxxxxxx> > >> >> > Cc: Anatoly Burakov <anatoly.burakov@xxxxxxxxx> > >> >> > Cc: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx> > >> >> > Cc: Magnus Karlsson <magnus.karlsson@xxxxxxxxx> > >> >> > Cc: Maryam Tahhan <mtahhan@xxxxxxxxxx> > >> >> > Cc: xdp-hints@xxxxxxxxxxxxxxx > >> >> > Cc: netdev@xxxxxxxxxxxxxxx > >> >> > Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx> > >> >> > --- > >> >> > Documentation/bpf/xdp-rx-metadata.rst | 90 +++++++++++++++++++++++++++ > >> >> > 1 file changed, 90 insertions(+) > >> >> > create mode 100644 Documentation/bpf/xdp-rx-metadata.rst > >> >> > > >> >> > diff --git a/Documentation/bpf/xdp-rx-metadata.rst b/Documentation/bpf/xdp-rx-metadata.rst > >> >> > new file mode 100644 > >> >> > index 000000000000..498eae718275 > >> >> > --- /dev/null > >> >> > +++ b/Documentation/bpf/xdp-rx-metadata.rst > >> >> > >> >> I think you need to add this to Documentation/bpf/index.rst. Or even > >> >> better, maybe it's time to add an xdp/ subdirectory and put all docs > >> >> there? Don't want to block your patchset from bikeshedding on this > >> >> point, so for now it's fine to just put it in > >> >> Documentation/bpf/index.rst until we figure that out. > >> > > >> > Maybe let's put it under Documentation/networking/xdp-rx-metadata.rst > >> > and reference form Documentation/networking/index.rst? Since it's more > >> > relevant to networking than the core bpf? > >> > > >> >> > @@ -0,0 +1,90 @@ > >> >> > +=============== > >> >> > +XDP RX Metadata > >> >> > +=============== > >> >> > + > >> >> > +XDP programs support creating and passing custom metadata via > >> >> > +``bpf_xdp_adjust_meta``. This metadata can be consumed by the following > >> >> > +entities: > >> >> > >> >> Can you add a couple of sentences to this intro section that explains > >> >> what metadata is at a high level? > >> > > >> > I'm gonna copy-paste here what I'm adding, feel free to reply back if > >> > still unclear. (so we don't have to wait another week to discuss the > >> > changes) > >> > > >> > XDP programs support creating and passing custom metadata via > >> > ``bpf_xdp_adjust_meta``. The metadata can contain some extra information > >> > about the packet: timestamps, hash, vlan and tunneling information, etc. > >> > This metadata can be consumed by the following entities: > >> > >> This is not really accurate, though? The metadata area itself can > >> contain whatever the XDP program wants it to, and I think you're > >> conflating the "old" usage for arbitrary storage with the driver-kfunc > >> metadata support. > >> > >> I think we should clear separate the two: the metadata area is just a > >> place to store data (and is not consumed by the stack, except that > >> TC-BPF programs can access it), and the driver kfuncs are just a general > >> way to get data out of the drivers (and has nothing to do with the > >> metadata area, you can just get the data into stack variables). > >> > >> While it would be good to have a documentation of the general metadata > >> area stuff somewhere, I don't think it necessarily have to be part of > >> this series, so maybe just stick to documenting the kfuncs? > > > > Maybe I can reword to something like below? > > > > The metadata can be used to store some extra information about the > > packet timestamps, hash, vlan and tunneling information, etc. > > > > This way we are not actually defining what it is, but hinting about > > how it's commonly used? > > Sent another reply to the original patch with some comments that are > hopefully a bit more constructive :) Thanks, everything makes sense, will incorporate. I'll also try to share the patches privately with you sometime tomorrow maybe; not super comfortable sending them out with a bunch of changes on top of your authorship without some kind of ack from you :-) > -Toke >
