[+lkml, Masahiro, Alexei and Daniel] On Tue, Nov 12, 2019 at 04:56:39PM +0800, Xiao Yang wrote: > With your patch[1], I alway get the following error when building > tools/bpf: In case people want to reproduce this, my branch is here: https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=lto > ---------------------------------------------------------------------------------- > > make -C tools/bpf/ > make: Entering directory > '/usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/tools/bpf' > > Auto-detecting system features: > ... libbfd: [ on ] > ... disassembler-four-args: [ OFF ] > > CC bpf_jit_disasm.o > CC bpf_dbg.o > In file included from > /usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/include/uapi/linux/filter.h:9:0, > from > /usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/tools/bpf/bpf_dbg.c:41: > /usr/src/perf_selftests-x86_64-rhel-7.6-642a312d47ceb54603630d9d04f5052f3b46d9a3/include/linux/compiler.h:247:24: > fatal error: asm/rwonce.h: No such file or directory > #include <asm/rwonce.h> > ^ > compilation terminated. > Makefile:61: recipe for target 'bpf_dbg.o' failed > make: *** [bpf_dbg.o] Error 1 > make: *** Waiting for unfinished jobs.... > make: Leaving directory > > ---------------------------------------------------------------------------------- > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/commit/?h=lto&id=642a312d47ceb54603630d9d04f5052f3b46d9a3 > > It seems that include/linux/compiler.h cannot find the asm/rwonce.h because > tools/bpf/Makefile doesn't include arch/*/include/generated/asm/rwonce.h. The problem with referring to the generated files is that they don't exist unless you've configured the main source directory. The real problem here seems to be that tools/bpf/ refers directly to header files in the kernel sources without any understanding of kbuild, and therefore mandatory-y headers simply don't exist when it goes looking for them. Perhaps it's possible to introduce a dependency on a top-level "make asm-generic" so that we can reference the generated headers from the arch directly. Thoughts? Will
