On Thu, Dec 19, 2019 at 7:26 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote: > > I got the following error when I tried to build perf on a read-only > filesystem with O=dir option. > > $ cd /some/where/ro/linux/tools/perf > $ make O=$HOME/build/perf > ... > CC /home/namhyung/build/perf/lib.o > /bin/sh: bpf_helper_defs.h: Read-only file system > make[3]: *** [Makefile:184: bpf_helper_defs.h] Error 1 > make[2]: *** [Makefile.perf:778: /home/namhyung/build/perf/libbpf.a] Error 2 > make[2]: *** Waiting for unfinished jobs.... > LD /home/namhyung/build/perf/libperf-in.o > AR /home/namhyung/build/perf/libperf.a > PERF_VERSION = 5.4.0 > make[1]: *** [Makefile.perf:225: sub-make] Error 2 > make: *** [Makefile:70: all] Error 2 > > It was becaused bpf_helper_defs.h was generated in current directory. > Move it to OUTPUT directory. > > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx> > --- > tools/lib/bpf/Makefile | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile > index 99425d0be6ff..2f42a35f4634 100644 > --- a/tools/lib/bpf/Makefile > +++ b/tools/lib/bpf/Makefile > @@ -159,7 +159,7 @@ all: fixdep > > all_cmd: $(CMD_TARGETS) check > > -$(BPF_IN_SHARED): force elfdep bpfdep bpf_helper_defs.h > +$(BPF_IN_SHARED): force elfdep bpfdep $(OUTPUT)bpf_helper_defs.h btw, there is a lot of $(OUTPUT)bpf_helper_defs.h repetition, could you please extract it into a variable, similar to BPF_IN_SHARED and others? E.g., just BPF_HELPER_DEFS would work. Thanks! > @(test -f ../../include/uapi/linux/bpf.h -a -f ../../../include/uapi/linux/bpf.h && ( \ > (diff -B ../../include/uapi/linux/bpf.h ../../../include/uapi/linux/bpf.h >/dev/null) || \ > echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf.h' differs from latest version at 'include/uapi/linux/bpf.h'" >&2 )) || true > @@ -177,12 +177,12 @@ $(BPF_IN_SHARED): force elfdep bpfdep bpf_helper_defs.h > echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/if_xdp.h' differs from latest version at 'include/uapi/linux/if_xdp.h'" >&2 )) || true > $(Q)$(MAKE) $(build)=libbpf OUTPUT=$(SHARED_OBJDIR) CFLAGS="$(CFLAGS) $(SHLIB_FLAGS)" [...]
