Building bpftool with OUTPUT set breaks

[Lorenz Bauer <lmb@cloudflare.com>]

Hello,

On 5.2 and current bpf-next, the following fails:

$ make -C tools/bpf/bpftool OUTPUT=/tmp/tmp.NUSttIbAYw/
make: Entering directory '/home/lorenz/dev/bpf-next/tools/bpf/bpftool'

Auto-detecting system features:
...                        libbfd: OFF
...        disassembler-four-args: OFF

  CC       /tmp/tmp.NUSttIbAYw/map_perf_ring.o
<snip>
  CC       /tmp/tmp.NUSttIbAYw/disasm.o
make[1]: Entering directory '/home/lorenz/dev/bpf-next/tools/lib/bpf'

Auto-detecting system features:
...                        libelf: on
...                           bpf: on

  CC       /tmp/tmp.NUSttIbAYw/libbpf.o
<snip>
  CC       /tmp/tmp.NUSttIbAYw/btf_dump.o
  LD       /tmp/tmp.NUSttIbAYw/libbpf-in.o
  LINK     /tmp/tmp.NUSttIbAYw/libbpf.a
make[1]: Leaving directory '/home/lorenz/dev/bpf-next/tools/lib/bpf'
  LINK     /tmp/tmp.NUSttIbAYw/bpftool
/usr/bin/ld: /tmp/tmp.NUSttIbAYw/libbpf.a(libbpf-in.o): in function `do_btf':
(.text+0x105b0): multiple definition of `do_btf';
/tmp/tmp.NUSttIbAYw/btf.o:btf.c:(.text+0x11f0): first defined here
<snip>

I think the problem is that objects for both bpftool and libbpf end up
in the same directory
if OUTPUT is set. Does anybody know how to fix this?

Best
Lorenz

-- 
Lorenz Bauer  |  Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK

www.cloudflare.com