Re: Kernel 5.5.4 build fail for BPF-selftests with latest LLVM

[Jesper Dangaard Brouer]

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.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer