Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932429AbbFJC2H (ORCPT ); Tue, 9 Jun 2015 22:28:07 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:60328 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752115AbbFJC15 (ORCPT ); Tue, 9 Jun 2015 22:27:57 -0400 Message-ID: <55779FB0.7000809@huawei.com> Date: Wed, 10 Jun 2015 10:23:44 +0800 From: "Wangnan (F)" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Alexei Starovoitov , , , , , , , , , , CC: , , , , Subject: Re: [RFC PATCH v6 25/32] perf tools: Add 'bpf.' config section to perf default config References: <1433829036-23687-1-git-send-email-wangnan0@huawei.com> <1433829036-23687-26-git-send-email-wangnan0@huawei.com> <55777A17.7030000@plumgrid.com> <5577891C.5010904@huawei.com> <55778E54.5020800@plumgrid.com> In-Reply-To: <55778E54.5020800@plumgrid.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.111.66.109] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5241 Lines: 166 On 2015/6/10 9:09, Alexei Starovoitov wrote: > On 6/9/15 5:47 PM, Wangnan (F) wrote: >> >> >> On 2015/6/10 7:43, 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 $(LINUXINCLUDE) >>> automatically ? >>> You can even invoke such flag detector from perf via something like: >>> f = open /tmpdir/Makefile >>> fprintf(f, "obj-y := dummy.o\n"); >>> fprintf(f, "$(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 >>> >> >> That's cool, but could I implement it later? Introducing such stuffs > > I think --clang-opts shouldn't be introduced without > automatic flag finder. Ease of use is important. > What about automatic finder failed? It is possible that user environment doesn't have kbuild directory installed, should we make it another deadend? Then these 'ease of use' design is useless for me because in embedded area usecases are always rare. I think we can hide --clang-opt from cmdline, make it reside in .perfconfig only, and pop some messages on it when failure. Most of the time users need to config only once. Still not very hard, right? >> also introduces >> a lot of trouble tasks: >> >> 1. Dependency on make and kernel build. We should search make and kbuild >> dir dynamically >> and also gives users the right to specify them by theirselves. A lot >> of configuration >> options should be appended: --make-path=/path/to/make >> --kbuild-dir=kernel/build/dir >> in cmdline and >> [kbuild] >> make_path = /path/to/make >> kbuild_dir = /path/to/kbuild >> in .perfconfig. > > they're not mandatory. If 'make' is not in a PATH, it's dead end. > kernel build is very likely installed in /lib/modules/ > >> 2. Selection of architectures. Although currently we want it to work >> only when we dynamically >> compile a script, I think finally we should consider cross compiling >> bpf objects. Then cmdline >> generation becomes complex. Also, --arch and [kbuild.arch] should >> also be introduced. > > that's a rare use case. This one can be added later. > >> 3. Kernel dependency. Consider if kernel decides to change its >> interface... > > change what interface? 'make M=' ? sure. then lots of scripts will be > broken. > 'make M=' is unlikely to be changed. However it is possible for kernel to append more variable for specifying include, or devide $(NOSTDINC_FLAGS) $(LINUXINCLUDE) and $(EXTRA_CFLAGS) into smaller pieces. I'm not quite sure whether those make variables are part of kbuild interface. >> I think currently we can pop some messages to let user know how to get >> include dirs manually, >> let further patches to do it for them automatically. >> >> P.S. >> >> Have you tested your Makefile? It doesn't work for me: > > works as a charm: > $ cat /home/ast/ff/Makefile > obj-y := dummy.o > > $(obj)/%.o: $(src)/%.c > @echo -n "$(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS)" > > /tmp/xxx > $ make -s -C /w/net-next/bld_x64 M=/home/ast/ff dummy.o > $ cat /tmp/xxx > -nostdinc -isystem /usr/lib/gcc/x86_64-linux-gnu/4.7/include > -I../arch/x86/include -Iarch/x86/include/generated/uapi > -Iarch/x86/include/generated -I../include -Iinclude > -I../arch/x86/include/uapi -Iarch/x86/include/generated/uapi > -I../include/uapi -Iinclude/generated/uapi -include > ../include/linux/kconfig.h > Finally I made it work. dummy.c must exist on current directory. What we are talking about seems not very suit to be implemented using C. It should be implemented using a shell script: #!/usr/bin/env sh TMPDIR=`mktemp -d` cat << EOF > $TMPDIR/Makefile obj-y := dummy.o \$(obj)/%.o: \$(src)/%.c @echo -n "\$(NOSTDINC_FLAGS) \$(LINUXINCLUDE) \$(EXTRA_CFLAGS)" > $TMPDIR/cflags EOF touch $TMPDIR/dummy.c DEFAULT_KBUILD_DIR=/lib/modules/`uname -r`/build if ! test -d "$KBUILD_DIR" then KBUILD_DIR=$DEFAULT_KBUILD_DIR fi make -s -C $KBUILD_DIR M=$TMPDIR $OTHER_OPTS dummy.o 2>/dev/null cat $TMPDIR/cflags 2>/dev/null RET=$? rm -rf $TMPDIR exit $RET In this script, we can inject KBUILD_DIR and OTHER_OPTS to select another kbuild directory and "ARCH=" option. I'll embed this script in my next version. Thaknk you. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/