On Tue, Mar 21, 2023 at 6:32 AM Jesper Dangaard Brouer <jbrouer@xxxxxxxxxx> wrote: > > > > On 17/03/2023 22.13, Stanislav Fomichev wrote: > > On 03/17, Jesper Dangaard Brouer wrote: > >> When driver developers add XDP-hints kfuncs for RX hash it is > >> practical to print the return code in bpf_printk trace pipe log. > > > >> Print hash value as a hex value, both AF_XDP userspace and bpf_prog, > >> as this makes it easier to spot poor quality hashes. > > > >> Signed-off-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx> > > > > Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx> > > > > (with a small suggestion below, maybe can do separately?) > > > >> --- > >> .../testing/selftests/bpf/progs/xdp_hw_metadata.c | 9 ++++++--- > >> tools/testing/selftests/bpf/xdp_hw_metadata.c | 5 ++++- > >> 2 files changed, 10 insertions(+), 4 deletions(-) > [...] > >> diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c > >> b/tools/testing/selftests/bpf/xdp_hw_metadata.c > >> index 400bfe19abfe..f3ec07ccdc95 100644 > >> --- a/tools/testing/selftests/bpf/xdp_hw_metadata.c > >> +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c > >> @@ -3,6 +3,9 @@ > >> /* Reference program for verifying XDP metadata on real HW. > >> Functional test > >> * only, doesn't test the performance. > >> * > > > > [..] > > > >> + * BPF-prog bpf_printk info outout can be access via > >> + * /sys/kernel/debug/tracing/trace_pipe > > > > Maybe we should just dump the contents of > > /sys/kernel/debug/tracing/trace for every poll cycle? > > > > I think this belongs to a separate patch. SG. If you prefer to keep the comment let's also s/outout/outPut/. > > We can also maybe enable tracing in this program transparently? > > I usually forget 'echo 1 > > > /sys/kernel/debug/tracing/events/bpf_trace/bpf_trace_printk/enable' > > myself :-) > > > What is this trick? On the recent kernels I think this event has to be explicitly enabled for bpf_prink() to work? Not sure. That's why having something like enable_tracing() and dump_trace() here might be helpful for whoever is running the prog. > --Jesper >
