Re: Kernel 5.5.4 build fail for BPF-selftests with latest LLVM
From: Jesper Dangaard Brouer
Date: Wed Feb 19 2020 - 12:04:16 EST
On Wed, 19 Feb 2020 08:41:27 -0800
Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote:
> On Wed, Feb 19, 2020 at 4:30 AM Jesper Dangaard Brouer
> <brouer@xxxxxxxxxx> wrote:
> > I'm willing to help out, such that we can do either version or feature
> > detection, to either skip compiling specific test programs or at least
> > give users a proper warning of they are using a too "old" LLVM version.
> > progs/test_core_reloc_bitfields_probed.c:47:13: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration]
> > out->ub1 = BPF_CORE_READ_BITFIELD_PROBED(in, ub1);
> imo this is proper warning message already.
This is an error, not a warning. The build breaks as the make process stops.
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat