On Wed, Feb 10, 2021 at 11:26:28AM -0800, Andrii Nakryiko wrote:

SNIP

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Can't reproduce it. It works in all kinds of variants (relative and
absolute O=, clean and not clean trees, etc). Jiri, please check as
well.

Odd, this reproduces for me on a completely clean checkout of bpf-next:

$ git clone --depth=1 https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/

$ cd bpf-next

$ make -s O=build distclean
../../scripts/Makefile.include:4: *** O=/tmp/bpf-next/build/tools/bpf/resolve_btfids does not exist.  Stop.

I do not really see how this could be environment related. It seems like
this comes from tools/scripts/Makefile.include, where there is no
guarantee that $(O) is created before being used like in the main
Makefile?

right, we need to handle the case where tools/bpf/resolve_btfids
does not exist, patch below fixes it for me

jirka

Looks good to me, please send it as a proper patch to bpf-next.

But I'm curious, why is objtool not doing something like that? Is it
not doing clean at all? Or does it do it in some different way?

yes, it's not connected to global make clean

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---

diff --git a/Makefile b/Makefile
index 159d9592b587..ce9685961abe 100644
--- a/Makefile
+++ b/Makefile

@@ -1088,8 +1088,14 @@ endif

 PHONY += resolve_btfids_clean

+resolve_btfids_O = $(abspath $(objtree))/tools/bpf/resolve_btfids
+
+# tools/bpf/resolve_btfids directory might not exist
+# in output directory, skip its clean in that case
 resolve_btfids_clean:
-       $(Q)$(MAKE) -sC $(srctree)/tools/bpf/resolve_btfids O=$(abspath $(objtree))/tools/bpf/resolve_btfids clean
+ifneq (,$(wildcard $(resolve_btfids_O)))

nit: kind of backwards, usually it's in a `ifneq($var,)` form

ok

thanks,
jirka