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authorKumar Kartikeya Dwivedi <memxor@gmail.com>2025-07-03 13:48:17 -0700
committerAlexei Starovoitov <ast@kernel.org>2025-07-03 19:30:07 -0700
commit876f5ebd58a9ac42f48a7ead3d5b274a314e0ace (patch)
treefb5461f331ddb21c035abb683ba70362363443cf /tools/bpf/bpftool/Documentation
parent3bbc1ba9cc0d9a7ccc194883489a4e460ca5080b (diff)
bpftool: Add support for dumping streams
Add support for printing the BPF stream contents of a program in bpftool. The new bpftool prog tracelog command is extended to take stdout and stderr arguments, and then the prog specification. The bpf_prog_stream_read() API added in previous patch is simply reused to grab data and then it is dumped to the respective file. The stdout data is sent to stdout, and stderr is printed to stderr. Cc: Quentin Monnet <qmo@kernel.org> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Link: https://lore.kernel.org/r/20250703204818.925464-12-memxor@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/bpf/bpftool/Documentation')
-rw-r--r--tools/bpf/bpftool/Documentation/bpftool-prog.rst7
1 files changed, 7 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
index da3152c16228..f69fd92df8d8 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
@@ -35,6 +35,7 @@ PROG COMMANDS
| **bpftool** **prog attach** *PROG* *ATTACH_TYPE* [*MAP*]
| **bpftool** **prog detach** *PROG* *ATTACH_TYPE* [*MAP*]
| **bpftool** **prog tracelog**
+| **bpftool** **prog tracelog** [ { **stdout** | **stderr** } *PROG* ]
| **bpftool** **prog run** *PROG* **data_in** *FILE* [**data_out** *FILE* [**data_size_out** *L*]] [**ctx_in** *FILE* [**ctx_out** *FILE* [**ctx_size_out** *M*]]] [**repeat** *N*]
| **bpftool** **prog profile** *PROG* [**duration** *DURATION*] *METRICs*
| **bpftool** **prog help**
@@ -179,6 +180,12 @@ bpftool prog tracelog
purposes. For streaming data from BPF programs to user space, one can use
perf events (see also **bpftool-map**\ (8)).
+bpftool prog tracelog { stdout | stderr } *PROG*
+ Dump the BPF stream of the program. BPF programs can write to these streams
+ at runtime with the **bpf_stream_vprintk**\ () kfunc. The kernel may write
+ error messages to the standard error stream. This facility should be used
+ only for debugging purposes.
+
bpftool prog run *PROG* data_in *FILE* [data_out *FILE* [data_size_out *L*]] [ctx_in *FILE* [ctx_out *FILE* [ctx_size_out *M*]]] [repeat *N*]
Run BPF program *PROG* in the kernel testing infrastructure for BPF,
meaning that the program works on the data and context provided by the