On Tue, 24 Jun 2025 at 14:01, Jiri Olsa <olsajiri@xxxxxxxxx> wrote: > > On Mon, Jun 23, 2025 at 08:12:42PM -0700, Kumar Kartikeya Dwivedi wrote: > > Add support for a stream API to the kernel and expose related kfuncs to > > BPF programs. Two streams are exposed, BPF_STDOUT and BPF_STDERR. These > > can be used for printing messages that can be consumed from user space, > > thus it's similar in spirit to existing trace_pipe interface. > > > > The kernel will use the BPF_STDERR stream to notify the program of any > > errors encountered at runtime. BPF programs themselves may use both > > streams for writing debug messages. BPF library-like code may use > > BPF_STDERR to print warnings or errors on misuse at runtime. > > just curious, IIUC we can't mix the output of the streams when we dump > them, right? I wonder it'd be handy to be able to get combined output > and see messages from bpf programs sorted out with messages from kernel > Yeah, this is a good point. Right now, no, in the sense that sequentiality is definitely broken across the two streams. We can force print a timestamp for every message and do the sorting from bpftool side, or it can just be piped to sort after dumping both stdout and stderr. Output will look like trace_pipe with some fixed format before the actual message. WDYT? Others are also welcome to chime in. > thanks, > jirka > > > > [...]
