linux/tools
Quentin Monnet e0a43aa3e4 tools: bpftool: ignore make built-in rules for getting kernel version
Bpftool calls the toplevel Makefile to get the kernel version for the
sources it is built from. But when the utility is built from the top of
the kernel repository, it may dump the following error message for
certain architectures (including x86):

    $ make tools/bpf
    [...]
    make[3]: *** [checkbin] Error 1
    [...]

This does not prevent bpftool compilation, but may feel disconcerting.
The "checkbin" arch-dependent target is not supposed to be called for
target "kernelversion", which is a simple "echo" of the version number.

It turns out this is caused by the make invocation in tools/bpf/bpftool,
which attempts to find implicit rules to apply. Extract from debug
output:

    Reading makefiles...
    Reading makefile 'Makefile'...
    Reading makefile 'scripts/Kbuild.include' (search path) (no ~ expansion)...
    Reading makefile 'scripts/subarch.include' (search path) (no ~ expansion)...
    Reading makefile 'arch/x86/Makefile' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.kcov' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.gcc-plugins' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.kasan' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.extrawarn' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.ubsan' (search path) (no ~ expansion)...
    Updating makefiles....
     Considering target file 'scripts/Makefile.ubsan'.
      Looking for an implicit rule for 'scripts/Makefile.ubsan'.
      Trying pattern rule with stem 'Makefile.ubsan'.
    [...]
      Trying pattern rule with stem 'Makefile.ubsan'.
      Trying implicit prerequisite 'scripts/Makefile.ubsan.o'.
      Looking for a rule with intermediate file 'scripts/Makefile.ubsan.o'.
       Avoiding implicit rule recursion.
       Trying pattern rule with stem 'Makefile.ubsan'.
       Trying rule prerequisite 'prepare'.
       Trying rule prerequisite 'FORCE'.
      Found an implicit rule for 'scripts/Makefile.ubsan'.
        Considering target file 'prepare'.
         File 'prepare' does not exist.
          Considering target file 'prepare0'.
           File 'prepare0' does not exist.
            Considering target file 'archprepare'.
             File 'archprepare' does not exist.
              Considering target file 'archheaders'.
               File 'archheaders' does not exist.
               Finished prerequisites of target file 'archheaders'.
              Must remake target 'archheaders'.
    Putting child 0x55976f4f6980 (archheaders) PID 31743 on the chain.

To avoid that, pass the -r and -R flags to eliminate the use of make
built-in rules (and while at it, built-in variables) when running
command "make kernelversion" from bpftool's Makefile.

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-08-31 00:38:16 +02:00
..
accounting
arch tools headers UAPI: Update tools's copy of mman.h headers 2019-07-29 09:02:58 -03:00
bpf tools: bpftool: ignore make built-in rules for getting kernel version 2019-08-31 00:38:16 +02:00
build tools build: Check if gettid() is available before providing helper 2019-07-07 17:53:09 -03:00
cgroup
crypto
debugging
firewire
firmware Driver Core and debugfs changes for 5.3-rc1 2019-07-12 12:24:03 -07:00
gpio Bulk GPIO changes for the v5.3 kernel cycle: 2019-07-09 09:07:00 -07:00
hv
iio Second set of IIO device support, features, cleanups and minor fixes for 5.3. 2019-07-01 10:58:13 +02:00
include tools/bpf: sync bpf.h 2019-08-28 00:30:11 +02:00
io_uring
kvm/kvm_stat treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 499 2019-06-19 17:09:53 +02:00
laptop treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 505 2019-06-19 17:11:22 +02:00
leds
lib libbpf: use LFS (_FILE_OFFSET_BITS) instead of direct mmap2 syscall 2019-08-21 14:31:17 +02:00
memory-model tools/memory-model: Improve data-race detection 2019-06-24 09:08:54 -07:00
nfsd
objtool objtool: Improve UACCESS coverage 2019-07-25 08:36:39 +02:00
pci pci-v5.3-changes 2019-07-15 20:44:49 -07:00
pcmcia treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 247 2019-06-19 17:09:08 +02:00
perf perf tools: Fix perf.data documentation units for memory size 2019-07-29 09:03:43 -03:00
power kbuild: create *.mod with full directory path and remove MODVERDIR 2019-07-18 02:19:31 +09:00
scripts perf build: Do not use -Wshadow on gcc < 4.8 2019-07-23 09:04:54 -03:00
spi
testing selftests/bpf: remove wrong nhoff in flow dissector test 2019-08-28 00:39:43 +02:00
thermal/tmon
time
usb
virtio treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 482 2019-06-19 17:09:52 +02:00
vm tools/vm/slabinfo: add sorting info to help menu 2019-07-12 11:05:46 -07:00
wmi treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Makefile tools/power/x86: A tool to validate Intel Speed Select commands 2019-07-03 15:37:09 +03:00