Date: Thu, 11 Jun 2015 16:45:53 +0900
From: Namhyung Kim <namhyung@kernel.org>
To: Alexei Starovoitov <ast@plumgrid.com>
Cc: Wang Nan <wangnan0@huawei.com>, acme@kernel.org, brendan.d.gregg@gmail.com,
        daniel@iogearbox.net, masami.hiramatsu.pt@hitachi.com,
        paulus@samba.org, a.p.zijlstra@chello.nl, mingo@redhat.com,
        jolsa@kernel.org, dsahern@gmail.com, linux-kernel@vger.kernel.org,
        lizefan@huawei.com, hekuang@huawei.com, xiakaixu@huawei.com,
        pi3orama@163.com
Subject: Re: [RFC PATCH v6 25/32] perf tools: Add 'bpf.' config section to
 perf default config
Message-ID: <20150611074553.GB11184@sejong>
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 <55777A17.7030000@plumgrid.com>
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On Tue, Jun 09, 2015 at 04:43:19PM -0700, Alexei Starovoitov wrote:
> On 6/8/15 10:50 PM, Wang Nan wrote:
> >perf_bpf_config() is added to parse 'bpf' section in perf config file.
> >Following is an example:
> >
> >  [bpf]
> >    clang-path = /llvm/bin/x86_64-linux-clang"
> >    llc-path = /llvm/bin/x86_64-linux-llc"
> >    clang-opt = "-nostdinc -isystem /llvm/lib/clang/include -I/kernel/arch/x86/include ..."
> >    llc-opt = ""
> 
> a section to specify -I flags to compile prog.c is useful,
> but users shouldn't be populating it manually for kernel headers.
> How about adding a script that can figure out $(LINUXINCLUDE)
> automatically ?

Maybe a dummy question.  For what reason it needs such headers?  Is it
possible to have a (part of?) copy of needed bits in the perf source?

Thanks,
Namhyung


> You can even invoke such flag detector from perf via something like:
> f = open /tmpdir/Makefile
> fprintf(f, "obj-y := dummy.o\n");
> fprintf(f, "$(obj)/%%.o: $(src)/%%.c\n");
> fprintf(f, "\t@echo -n \"$(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS)\"
> > %s\n", cachefile);
> snprintf(cmd, "make -s -C /lib/modules/%s/build M=%s dummy.o",
>    uts_release, tmpdir);
> system(cmd);
> read flags from cachefile and cache it for the future.
> ...
> or as independent script that populates .perfconfig
> 
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