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> > and it will work as expected. Could you explain what would be the difference vs existing bpf_printk macro? Why these patches enable above to work ? > I haven't updated libbpf-provided helpers in > bpf_helpers.h for snprintf, seq_printf, and printk, because using > `static const char ___fmt[] = fmt;` trick is still efficient and doesn't fill > out the buffer at runtime (no copying), but it also enforces that format > string is compile-time string literal: > > const char *s = NULL; > > bpf_printk("hi"); /* works */ > bpf_printk(s); /* compilation error */ > > By passing fmt directly to bpf_trace_printk() would actually compile > bpf_printk(s) above with no warnings and will not work at runtime, which is > worse user experience, IMO. What is the example of "compile with no warning and not work at runtime" ?