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authorMasahiro Yamada <masahiroy@kernel.org>2020-07-01 22:29:36 +0300
committerMasahiro Yamada <masahiroy@kernel.org>2020-08-09 19:32:58 +0300
commit3ec8a5b33deacdeca4bef24fb15498a975e875ba (patch)
tree8e358066d252e9021b3c587d5562f20edc2847e4 /net/ipv4
parentcc8a51ca6f05ade72f7dd2624bc5f9b948e216fc (diff)
downloadlinux-3ec8a5b33deacdeca4bef24fb15498a975e875ba.tar.xz
kbuild: do not export LDFLAGS_vmlinux
When you clean the build tree for ARCH=arm, you may see the following error message from 'nm' command: $ make -j24 ARCH=arm clean CLEAN arch/arm/crypto CLEAN arch/arm/kernel CLEAN arch/arm/mach-at91 CLEAN arch/arm/mach-omap2 CLEAN arch/arm/vdso CLEAN certs CLEAN lib CLEAN usr CLEAN net/wireless CLEAN drivers/firmware/efi/libstub nm: 'arch/arm/boot/compressed/../../../../vmlinux': No such file /bin/sh: 1: arithmetic expression: expecting primary: " " CLEAN arch/arm/boot/compressed CLEAN drivers/scsi CLEAN drivers/tty/vt CLEAN arch/arm/boot CLEAN vmlinux.symvers modules.builtin modules.builtin.modinfo Even if you rerun the same command, the error message will not be shown despite vmlinux is already gone. To reproduce it, the parallel option -j is needed. Single thread cleaning always executes 'archclean', 'vmlinuxclean' in this order, so vmlinux still exists when arch/arm/boot/compressed/ is cleaned. Looking at arch/arm/boot/compressed/Makefile does not help understand the reason of the error message. Both KBSS_SZ and LDFLAGS_vmlinux are assigned with '=' operator, hence, they are not expanded unless used. Obviously, 'make clean' does not use them. In fact, the root cause exists in the top Makefile: export LDFLAGS_vmlinux Since LDFLAGS_vmlinux is an exported variable, LDFLAGS_vmlinux in arch/arm/boot/compressed/Makefile is expanded when scripts/Makefile.clean has a command to execute. This is why the error message shows up only when there exist build artifacts in arch/arm/boot/compressed/. Adding 'unexport LDFLAGS_vmlinux' to arch/arm/boot/compressed/Makefile will fix it as far as ARCH=arm is concerned, but I think the proper fix is to get rid of 'export LDFLAGS_vmlinux' from the top Makefile. LDFLAGS_vmlinux in the top Makefile contains linker flags for the top vmlinux. LDFLAGS_vmlinux in arch/arm/boot/compressed/Makefile is for arch/arm/boot/compressed/vmlinux. They just happen to have the same variable name, but are used for different purposes. Stop shadowing LDFLAGS_vmlinux. This commit passes LDFLAGS_vmlinux to scripts/link-vmlinux.sh via a command line parameter instead of via an environment variable. LD and KBUILD_LDFLAGS are exported, but I did the same for consistency. Anyway, they must be included in cmd_link-vmlinux to allow if_changed to detect the changes in LD or KBUILD_LDFLAGS. The following Makefiles are not affected: arch/arm/boot/compressed/Makefile arch/h8300/boot/compressed/Makefile arch/nios2/boot/compressed/Makefile arch/parisc/boot/compressed/Makefile arch/s390/boot/compressed/Makefile arch/sh/boot/compressed/Makefile arch/sh/boot/romimage/Makefile arch/x86/boot/compressed/Makefile They use ':=' or '=' to clear the LDFLAGS_vmlinux inherited from the top Makefile. We need to take a closer look at the impact to unicore32 and xtensa. arch/unicore32/boot/compressed/Makefile only uses '+=' operator for LDFLAGS_vmlinux. So, the decompressor previously inherited the linker flags from the top Makefile. However, commit 70fac51feaf2 ("unicore32 additional architecture files: boot process") was merged before commit 1f2bfbd00e46 ("kbuild: link of vmlinux moved to a script"). So, I rather consider this is a bug fix of 1f2bfbd00e46. arch/xtensa/boot/boot-elf/Makefile is also affected, but this is also considered a fix for the same reason. It did not inherit LDFLAGS_vmlinux when commit 4bedea945451 ("[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 2") was merged. I deleted $(LDFLAGS_vmlinux), which is now empty. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com>
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