On Mon, Aug 23, 2021 at 9:50 PM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > On Fri, Aug 20, 2021 at 7:59 PM Dave Marchevsky <davemarchevsky@xxxxxx> wrote: > > > > This helper is meant to be "bpf_trace_printk, but with proper vararg > > We have bpf_snprintf() and bpf_seq_printf() names for other BPF > helpers using the same approach. How about we call this one simply > `bpf_printf`? It will be in line with other naming, it is logical BPF > equivalent of user-space printf (which outputs to stderr, which in BPF > land is /sys/kernel/debug/tracing/trace_pipe). And it will be logical > to have a nice and short BPF_PRINTF() convenience macro provided by > libbpf. > > > support". Follow bpf_snprintf's example and take a u64 pseudo-vararg > > array. Write to dmesg using the same mechanism as bpf_trace_printk. > > Are you sure about the dmesg part?... bpf_trace_printk is outputting > into /sys/kernel/debug/tracing/trace_pipe. Actually I like bpf_trace_vprintk() name, since it makes it obvious that it's a flavor of bpf_trace_printk() and its quirks that users learned to deal with. I would reserve bpf_printf() for the future. We might have standalone bpf programs in the future (without user space component) and a better equivalent of stdin/stdout. clang -target bpf hello_world.c -o a.out; ./a.out should print to a terminal. Such future hello world in bpf would be using bpf_printf() or bpf_dprintf().
