Re: [PATCH 27/31] perf record: Support custom vmlinux path

From: Arnaldo Carvalho de Melo
Date: Tue Sep 01 2015 - 16:19:25 EST

Em Sat, Aug 29, 2015 at 04:22:01AM +0000, Wang Nan escreveu:
> From: He Kuang <hekuang@xxxxxxxxxx>
> Make perf-record command support --vmlinux option if BPF_PROLOGUE is on.

Ok, this should be supported, i.e. letting the user specify a vmlinux
path to use.

But it shouldn't be _required_, i.e. we have things like vmlinux_path to
try to find it in well known places.

Right now it will search for it in the process of trying to load its
symtab, but I think we should have a function that tries to find a
vmlinux that matches the build-id of the running kernel, for things that
want to have access directly to the ELF file with debuginfo without
having to load the symtab in a struct dso, etc.

I'll look at the next patches to check how you make use of this info...

- Arnaldo

> 'perf record' needs vmlinux as the source of DWARF info to generate
> prologue for BPF programs, so path of vmlinux should be specified.
> Short name 'k' has been taken by 'clockid'. This patch skips the short
> option name and use '--vmlinux' for vmlinux path.
> Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
> Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
> Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
> Cc: David Ahern <dsahern@xxxxxxxxx>
> Cc: He Kuang <hekuang@xxxxxxxxxx>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Cc: Kaixu Xia <xiakaixu@xxxxxxxxxx>
> Cc: Masami Hiramatsu <>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Paul Mackerras <paulus@xxxxxxxxx>
> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Cc: Zefan Li <lizefan@xxxxxxxxxx>
> Cc: pi3orama@xxxxxxx
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Link:
> ---
> tools/perf/builtin-record.c | 4 ++++
> 1 file changed, 4 insertions(+)
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 212718c..8eb39d5 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -1100,6 +1100,10 @@ struct option __record_options[] = {
> "clang binary to use for compiling BPF scriptlets"),
> OPT_STRING(0, "clang-opt", &llvm_param.clang_opt, "clang options",
> "options passed to clang when compiling BPF scriptlets"),
> + OPT_STRING(0, "vmlinux", &symbol_conf.vmlinux_name,
> + "file", "vmlinux pathname"),
> +#endif
> #endif
> };
> --
> 2.1.0
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