Re: Compile build issues with samples/bpf/ again

[Jesper Dangaard Brouer <brouer@redhat.com>]

On Wed, 30 Oct 2019 11:53:21 +0100
Björn Töpel <bjorn.topel@gmail.com> wrote:

> On Wed, 30 Oct 2019 at 11:43, Jesper Dangaard Brouer <brouer@redhat.com> wrote:
> >
> > Hi Maintainers,
> >
> > It is annoy to experience that simply building kernel tree samples/bpf/
> > is broken as often as it is.  Right now, build is broken in both DaveM
> > net.git and bpf.git.  ACME have some build fixes queued from Björn
> > Töpel. But even with those fixes, build (for samples/bpf/task_fd_query_user.c)
> > are still broken, as reported by Eric Sage (15 Oct), which I have a fix for.
> >  
> 
> Hmm, something else than commit e55190f26f92 ("samples/bpf: Fix build
> for task_fd_query_user.c")?

I see, you already fixed this... and it is in the bpf.git tree.

Then we only need your other fixes from ACME's tree.  I just cloned a
fresh version of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git
to check that 'make M=samples/bpf' still fails.


> > Could maintainers add building samples/bpf/ to their build test scripts?
> > (make headers_install && make M=samples/bpf)
> >
> > Also I discovered, the command to build have also recently changed:
> > - Before : make samples/bpf/   or  simply make in subdir samples/bpf/
> > - new cmd: make M=samples/bpf  and in subdir is broken
> >
> > Anyone knows what commit introduced this change?
> > (I need it for a fixes tag, when updating README.rst doc)

The make cmdline change is confusing, because the old command
'make samples/bpf/' reports success (remember last '/') ... this could
be why maintainers are not catching this.

See: old make cmd

 $ touch samples/bpf/*kern.c
 $ make samples/bpf/
   CALL    scripts/checksyscalls.sh
   CALL    scripts/atomic/check-atomics.sh
   DESCEND  objtool
 $


New make cmd fails:

$ make M=samples/bpf
samples/bpf/Makefile:209: WARNING: Detected possible issues with include path.
samples/bpf/Makefile:210: WARNING: Please install kernel headers locally (make headers_install).
  AR      samples/bpf/built-in.a
make -C /home/hawk/git/kernel/bpf/samples/bpf/../../tools/lib/bpf/ RM='rm -rf' LDFLAGS= srctree=/home/hawk/git/kernel/bpf/samples/bpf/../../ O=
  HOSTCC  samples/bpf/test_lru_dist
  HOSTCC  samples/bpf/sock_example
  HOSTCC  samples/bpf/fds_example.o
  HOSTLD  samples/bpf/fds_example
  HOSTCC  samples/bpf/sockex1_user.o
  HOSTLD  samples/bpf/sockex1
  HOSTCC  samples/bpf/sockex2_user.o
  HOSTLD  samples/bpf/sockex2
  HOSTCC  samples/bpf/bpf_load.o
  HOSTCC  samples/bpf/sockex3_user.o
  HOSTLD  samples/bpf/sockex3
/usr/bin/ld: samples/bpf/bpf_load.o: in function `do_load_bpf_file.part.2':
bpf_load.c:(.text+0x91a): undefined reference to `test_attr__enabled'
/usr/bin/ld: bpf_load.c:(.text+0x1403): undefined reference to `test_attr__open'
collect2: error: ld returned 1 exit status
make[1]: *** [scripts/Makefile.host:116: samples/bpf/sockex3] Error 1
make: *** [Makefile:1649: samples/bpf] Error 2

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