| Message ID | 20160428122053.16807.93143.stgit@firesoul (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2016/04/28 02:20PM, 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 I don't have an objection to this patch, but you didn't explain why/how this approach is better than just doing: PATH=~/git/llvm/build/bin make samples/bpf/ - Naveen -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 28 Apr 2016 18:51:33 +0530 "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote: > > 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 > > I don't have an objection to this patch, but you didn't explain why/how > this approach is better than just doing: > PATH=~/git/llvm/build/bin make samples/bpf/ It is almost the same. There is always another way to do the same. I explicitly use this to test different combinations of LLC and CLANG, in-order to validate Alexei's claim that older versions of CLANG could still work with a newer version of LLC. Thus, one use-case you approach cannot cover ;-) And clang seems to install a clang-3.9, which my solution also covers by explicitly specifying CLANG=clang-3.9, if several avail clang's are in the PATH.
On 2016/04/28 04:40PM, Jesper Dangaard Brouer wrote: > On Thu, 28 Apr 2016 18:51:33 +0530 > "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote: > > > > 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 > > > > I don't have an objection to this patch, but you didn't explain why/how > > this approach is better than just doing: > > PATH=~/git/llvm/build/bin make samples/bpf/ > > It is almost the same. There is always another way to do the same. > > I explicitly use this to test different combinations of LLC and CLANG, > in-order to validate Alexei's claim that older versions of CLANG could > still work with a newer version of LLC. Thus, one use-case you > approach cannot cover ;-) > > And clang seems to install a clang-3.9, which my solution also covers > by explicitly specifying CLANG=clang-3.9, if several avail clang's are > in the PATH. Ah, so a very niche use-case. Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> - Naveen -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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 $@
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 <brouer@redhat.com> Acked-by: Alexei Starovoitov <ast@kernel.org> --- samples/bpf/Makefile | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html