Messages in this thread | | | Date | Tue, 1 Sep 2015 18:33:28 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 27/31] perf record: Support custom vmlinux path |
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Em Wed, Sep 02, 2015 at 05:00:39AM +0800, pi3orama escreveu: > 发自我的 iPhone > > 在 2015年9月2日,上午4:21,Arnaldo Carvalho de Melo <acme@redhat.com> 写道: > > Em Tue, Sep 01, 2015 at 05:19:17PM -0300, Arnaldo Carvalho de Melo escreveu: > >> Em Sat, Aug 29, 2015 at 04:22:01AM +0000, Wang Nan escreveu: > >>> From: He Kuang <hekuang@huawei.com>
> >>> 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... > > > > So, the do it all from 'perf record' is in not yet in this patchkit, > > right? At least not in [ N/31 ] with N > 27, can you point me to it?
> It is for patch 8/31, which create kprobe points using add_perf_probe_events(). > > Before this patch it won't search debug info, prevent us use argument like this: > > SEC("lock_page=lock_page page->flags") > > or probe at line number, expect it finds a valid vmlinux from the default path.
Argh, that is because init_symbol_maps() uses symbol__init() that is also being used in 'perf record' by now... I.e. it was designed to be called just once, at tool start :-\
Will have to get my head around how this is being used to try to untangle this mess...
- Arnaldo
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