On 2015/06/05 1:22, Alexei Starovoitov wrote: > On 6/4/15 7:04 AM, Ingo Molnar wrote: >>>> # perf record -e bpf_source.c cmdline >>>> >>>> to create a eBPF filter from source, >>>> >>>> Use >>>> >>>> # perf record -e bpf_object.o cmdline >>>> >>>> to create a eBPF filter from object intermedia. >>>> >>>> Use >>>> >>>> # perf bpf compile bpf_source.c --kbuild=kernel-build-dir -o bpf_object.o >>>> >>>> to create the .o >>>> >>>> I think this should be enough. Currently only the second case has been >>>> implemented. >> So if users cannot actually generate .o files then it's premature to merge >> this in >> such an incomplete form! >> >> It should be possible to use a feature that we are merging. > > of course it's usable :) There is some confusion here. > To compile .c into .o one can easily use > clang -O2 -emit-llvm -c file.c -o - | llc -march=bpf -o file.o > any version of clang is ok, > llc needs to be fresh with bpf backend. > > For a lot of cases kernel headers are not needed, so above > will work fine. > For our TC examples we recommend to use 'bcc' alias: > bcc() { > clang -O2 -emit-llvm -c $1 -o - | llc -march=bpf -filetype=obj -o > "`basename $1 .c`.o" > } > then compiling as easy as 'bcc file.c' > > What Wang mentioned that we're working on is fully integrated 'bcc'. > It will use clang/llvm as libraries, so no intermediate steps will > be needed, but some folks will always have concerns about > ultra-embedded environments where even 20Mb of libllvm.so is too much. > > So I think we need to support both 'perf record -e file.[co]'
I think we'd better make 'perf record -e file.c' default and '-e file.o' should be an option. Thank you, > > -- Masami HIRAMATSU Linux Technology Research Center, System Productivity Research Dept. Center for Technology Innovation - Systems Engineering Hitachi, Ltd., Research & Development Group E-mail: masami.hiramatsu...@hitachi.com -- 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/