On 2/3/21 12:34 PM, Andrii Nakryiko wrote: > Libbpf's Makefile relies on Linux tools infrastructure's feature detection > framework, but libbpf's needs are very modest: it detects the presence of > libelf and libz, both of which are mandatory. So it doesn't benefit much from > the framework, but pays significant costs in terms of maintainability and > debugging experience, when something goes wrong. The other feature detector, > testing for the presernce of minimal BPF API in system headers is long > obsolete as well, providing no value. > > So stop using feature detection and just assume the presence of libelf and > libz during build time. Worst case, user will get a clear and actionable > linker error, e.g.: > > /usr/bin/ld: cannot find -lelf > > On the other hand, we completely bypass recurring issues various users > reported over time with false negatives of feature detection (libelf or libz > not being detected, while they are actually present in the system). > > Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> > Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > --- > tools/lib/bpf/.gitignore | 1 - > tools/lib/bpf/Makefile | 47 ++++------------------------------------ > 2 files changed, 4 insertions(+), 44 deletions(-) Hi Andrii, This does indeed fix the build problems that I was seeing, so I can add: Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> but in the long term I think that features/libs/etc. that are used should be checked for instead of being used blindly... IMO. Thanks. -- ~Randy
