Em Tue, Nov 11, 2014 at 01:24:38PM +0900, Namhyung Kim escreveu: > Hi Peter, > > On Mon, Nov 10, 2014 at 9:11 PM, Peter Zijlstra <pet...@infradead.org> wrote: > > On Mon, Nov 10, 2014 at 03:33:11PM +0900, Namhyung Kim wrote: > >> Hmm.. I don't think it's specific to the minimal elf parser. The return > >> value of dso__load_sym() is a number of symbols found so when it sees a > >> dso with 0 symbols it'll fall back to the next option IMHO (not > >> tested). Did you see a problem with the current code? > > > > So your patch: > > > > +++ b/tools/perf/util/symbol-minimal.c > > @@ -335,6 +335,9 @@ int dso__load_sym(struct dso *dso, struct map *map > > __maybe_unused, > > unsigned char *build_id[BUILD_ID_SIZE]; > > int ret; > > > > + if (dso->kernel) > > + return 0; /* always use kallsyms */ > > + > > > > changes the symbol-minimal.c file to add this exception. That is very > > much specific to the minimal elf parser, or am I just seeing things? > > What minimal parser does here is just skip kernel dsos (vmlinux) since > it didn't deal with all the details of parsing vmlinux currently. > > > > > > What I was saying, why not have a util/symbol.c change that disregards > > all DSOs with 0 symbols in. > > The util/symbol.c doesn't need this because it can handle vmlinux > reliably. So after reading symbol table, it'll use the dso if it
symbol.c should not be able to handle anything, since the actual ELF loader is in symbol-elf.c or simbol-minimal.c, no? I.e.: symbol.c::dso__load() symbol.c::dso__load_kernel_sym() symbol.c::dso__load_vmlinux() And then it heads into one of the ELF loaders, right now, without your patch, I see, when the minimal loader is used: symbol-minimal.c::dso__load_sym() reads the build-id and if it works, returns 1, which is a bug, it should return 0 in this case, possibly -1 if it doesn't read the build-id :-\ I.e. it should return 0, because that way it signals: "I can't read it, thus no symbols were loaded, symbol.c: please go on looking for them somewhere else, kallsyms perhaps?". And this is the bug, probably. Now to look at your patches to see if this is touched somehow... > actually contains symbols or fallback to next dso if it has 0 symbols. > IOW it already disregards all dsos with 0 symbols in. See above. > -- > Thanks, > Namhyung -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/