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samples/bpf: add back functionality to redefine LLC command

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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 128d1514be ("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: 128d1514be ("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>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jesper Dangaard Brouer 2016-04-28 14:20:53 +02:00 committed by David S. Miller
parent c23846c143
commit 6ccfba75d3
1 changed files with 5 additions and 1 deletions
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6
samples/bpf/Makefile
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@ -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 $@