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Date:   Fri, 6 Jan 2023 17:29:44 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>,
        linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: nm vmlinux error in arch/arm reappears after upgrade to make 4.4
Message-ID: <Y7i8+EjwdnhHtlrr@dev-arch.thelio-3990X>
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Hi Masahiro,

My distribution recently updated their version of make to 4.4 from 4.3,
after which I notice the following error from nm when building ARCH=arm
kernels, which I thought that this was supposed to be resolved with
commit 3ec8a5b33dea ("kbuild: do not export LDFLAGS_vmlinux") but the
tree clearly has this and it is not visible while just running clean (I
have to build zImage to see it):

  $ git show -s --format='%h ("%s")'
  512dee0c00ad ("Merge tag 'x86-urgent-2023-01-04' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")

  $ make --version | head -1
  GNU Make 4.4

  $ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- O=build defconfig zImage
  arm-linux-gnueabi-nm: 'arch/arm/boot/compressed/../../../../vmlinux': No such file

vs.

  $ make --version | head -1
  GNU Make 4.3

  $ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- O=build defconfig zImage

I bisected make to see what change causes this and I landed on
commit 98da874c ("[SV 10593] Export variables to $(shell ...)
commands") [1], which certainly seems like a reasonable commit to
blame but I am not sure how exactly it factors in here.

If you need any more information on reproducing this, I am happy to
provide it (CROSS_COMPILE is just the toolchains from kernel.org).

[1]: https://git.savannah.gnu.org/cgit/make.git/commit/?id=98da874c43035a490cdca81331724f233a3d0c9a

Cheers,
Nathan