14:38 <invano> hi all, hi fche. I've been able to add dwarf-less support for mips abi o32 and I'm currently dealing with uprobes, still mips. I can see, when compiling and elf with uprobes, the arguments for the NT_STAPSDTs are expressed as "$<number" that should correspond to each register. However, seems like stap cannot translate those arguments e.g. "Can't parse SDT_V3 operand '$5' [man error::sdt]: identifier '$arg2' at"

14:40 <fche> invano, probably a straightforward porting work in tapsets.cxx

14:40 <fche> where the translator decodes architecture-specific asm operator syntaxes

14:40 <invano> probably a mismatch between how the registers are called and how stap tries to retrieve them?

14:40 <invano> exactly

14:41 <invano> ok just wanted to check if you already knew anything about this. I proceed then

14:42 <fche> sdt_uprobe_var_expanding_visitor::visit_target_symbol_arg start there

14:42 <fche> note some mips stuff is in place already

14:42 <invano> thanks fche. I think I'm gonna issue a mips patch as soon as I finish, also to include mips o32 support

14:43 <fche> righto

14:43 <fche> thanks1

17:22 <baotiao> hello. what is the relation between kprobe and systemtap. I think systemtap is a wrapper of kprobe. is it right?

17:22 <fche> kprobes are an intra-kernel api

17:23 <fche> systemtap is a language for writing programs, which may execute partly using the kprobes api

17:26 <baotiao> fche: thank you. I find systemtap can only stap function which must have kernel symbol.

17:27 <fche> You're probably referring to debugging information. Different systemtap scripts require different levels of data. Many scripts can run with no debuginfo.

17:29 <fche> e.g. stap -e 'probe kprobe.function("sys_open") { println (register("rax")) }' needs none

17:30 <baotiao> you are right

17:33 <baotiao> but If I want to probe this one. sudo stap -e 'probe kernel.function("madvise_behavior_valid") { println ("hello") }'

17:34 <baotiao> I can find the code in file mm/madvise.c, but it tell me that I can't probe it. The reason I guess is that this function is static, and " cat /proc/kallsyms| grep madvise_behavior_valid" return nothing

17:36 <fche> or it could be inlined. yeah in such a case you need debuginfo (and good quality too)

17:39 <baotiao> I have add the debuginfo in this kernel, but it still return the error. can you tell me what do you mean by good quality?