Messages in this thread | | | Date | Thu, 04 Jun 2015 09:22:23 -0700 | From | Alexei Starovoitov <> | Subject | Re: [GIT PULL 0/6] perf/core improvements and fixes |
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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]'
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