From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: [net-next PATCH 1/4] samples/bpf: add back functionality to redefine LLC command Date: Tue, 26 Apr 2016 13:36:59 +0200 Message-ID: <571F52DB.7050904@iogearbox.net> References: <20160426110828.20716.13392.stgit@firesoul> <20160426110917.20716.43051.stgit@firesoul> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: bblanco@plumgrid.com, borkmann@iogearbox.net, alexei.starovoitov@gmail.com, linux-kbuild@vger.kernel.org To: Jesper Dangaard Brouer , netdev@vger.kernel.org Return-path: In-Reply-To: <20160426110917.20716.43051.stgit@firesoul> Sender: linux-kbuild-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 04/26/2016 01:09 PM, Jesper Dangaard Brouer wrote: > It is practical to be-able-to redefine the location of the LLVM > command 'llc', because not all distros have a LLVM version with bpf > target support. Thus, it is sometimes required to compile LLVM from > source, and sometimes it is not desired to overwrite the distros > default LLVM version. > > This feature was removed with 128d1514be35 ("samples/bpf: Use llc in > PATH, rather than a hardcoded value"). > > Add this features back. Note that it is possible to redefine the LLC > on the make command like: > > make samples/bpf/ LLC=~/git/llvm/build/bin/llc > > Fixes: 128d1514be35 ("samples/bpf: Use llc in PATH, rather than a hardcoded value") > Signed-off-by: Jesper Dangaard Brouer > --- > samples/bpf/Makefile | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile > index 744dd7a16144..5bae9536f100 100644 > --- a/samples/bpf/Makefile > +++ b/samples/bpf/Makefile > @@ -81,10 +81,14 @@ HOSTLOADLIBES_spintest += -lelf > HOSTLOADLIBES_map_perf_test += -lelf -lrt > HOSTLOADLIBES_test_overhead += -lelf -lrt > > +# Allows pointing LLC to a LLVM backend with bpf support, redefine on cmdline: > +# make samples/bpf/ LLC=~/git/llvm/build/bin/llc > +LLC ?= llc > + > # asm/sysreg.h - inline assembly used by it is incompatible with llvm. > # But, there is no easy way to fix it, so just exclude it since it is > # useless for BPF samples. > $(obj)/%.o: $(src)/%.c > clang $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) \ > -D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \ > - -O2 -emit-llvm -c $< -o -| llc -march=bpf -filetype=obj -o $@ > + -O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf -filetype=obj -o $@ Why not doing the same for clang? True that we're not using 'clang -target bpf' here, but when someone builds llvm from git, it's very likely that clang is cloned and built along with it.