Odd kbuild behaviour

Russell King (Oracle) linux at armlinux.org.uk
Thu Aug 11 07:20:43 PDT 2022 

Hi,

Please can someone try to explain what is going on when I ask for a .S
file to be built to an object with 5.19 and GNU make 4.3 from Debian
Bullseye (although I don't think this is a make version issue):

$ rm ../build/multi/arch/arm/lib/findbit.o
$ make -j2 CROSS_COMPILE="arm-linux-gnueabihf-" ARCH="arm" O=../build/multi arch/arm/lib/findbit.o
make[1]: Entering directory '/home/rmk/git/build/multi'
  GEN     Makefile
  CALL    /home/rmk/git/linux-rmk/scripts/atomic/check-atomics.sh
  CALL    /home/rmk/git/linux-rmk/scripts/checksyscalls.sh
make[3]: *** No rule to make target 'arch/arm/lib/findbit.o'.  Stop.
make[2]: *** [/home/rmk/git/linux-rmk/scripts/Makefile.build:441: __build] Error 2
make[1]: *** [/home/rmk/git/linux-rmk/Makefile:1843: arch/arm] Error 2
make[1]: *** Waiting for unfinished jobs....
  AS      arch/arm/lib/findbit.o
make[1]: Leaving directory '/home/rmk/git/build/multi'
make: *** [Makefile:219: __sub-make] Error 2

If I re-run it without removing the generated object, I get:

make[1]: Entering directory '/home/rmk/git/build/multi'
  GEN     Makefile
  CALL    /home/rmk/git/linux-rmk/scripts/atomic/check-atomics.sh
  CALL    /home/rmk/git/linux-rmk/scripts/checksyscalls.sh
make[3]: Nothing to be done for 'arch/arm/lib/findbit.o'.
make[1]: Leaving directory '/home/rmk/git/build/multi'

Note the "make[3]:" line, which ought not be there.

If I run make with V=1 in addition:

$ rm ../build/multi/arch/arm/lib/findbit.o
$ make -j2 CROSS_COMPILE="arm-linux-gnueabihf-" ARCH="arm"  O=../build/multi arch/arm/lib/findbit.o V=1
make -C /home/rmk/git/build/multi -f /home/rmk/git/linux-rmk/Makefile arch/arm/lib/findbit.o
make[1]: Entering directory '/home/rmk/git/build/multi'
if [ -f /home/rmk/git/linux-rmk/.config -o \
         -d /home/rmk/git/linux-rmk/include/config -o \
         -d /home/rmk/git/linux-rmk/arch/arm/include/generated ]; then \
        echo >&2 "***"; \
        echo >&2 "*** The source tree is not clean, please run 'make ARCH=arm mrproper'"; \
        echo >&2 "*** in /home/rmk/git/linux-rmk";\
        echo >&2 "***"; \
        false; \
fi
make -f /home/rmk/git/linux-rmk/scripts/Makefile.build obj=arch/arm/tools uapi
ln -fsn /home/rmk/git/linux-rmk source
  { echo "# Automatically generated by /home/rmk/git/linux-rmk/Makefile: don't edit"; echo "include /home/rmk/git/linux-rmk/Makefile"; } > Makefile
test -e .gitignore || \
{ echo "# this is build directory, ignore it"; echo "*"; } > .gitignore
make -f /home/rmk/git/linux-rmk/scripts/Makefile.build obj=scripts/basic
set -e; mkdir -p include/config/; trap "rm -f include/config/.kernel.release.tmp" EXIT; { echo "5.19.0$(sh /home/rmk/git/linux-rmk/scripts/setlocalversion /home/rmk/git/linux-rmk)"; } > include/config/.kernel.release.tmp; if [ ! -r include/config/kernel.release ] || ! cmp -s include/config/kernel.release include/config/.kernel.release.tmp; then : '  UPD     include/config/kernel.release'; mv -f include/config/.kernel.release.tmp include/config/kernel.release; fi
make -f /home/rmk/git/linux-rmk/scripts/Makefile.asm-generic obj=arch/arm/include/generated/uapi/asm \
generic=include/uapi/asm-generic
set -e; mkdir -p include/generated/uapi/linux/; trap "rm -f include/generated/uapi/linux/.version.h.tmp" EXIT; {        if [ 0 -gt 255 ]; then echo \#define LINUX_VERSION_CODE 332799; else echo \#define LINUX_VERSION_CODE 332544; fi; echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)))'; echo \#define LINUX_VERSION_MAJOR 5; echo \#define LINUX_VERSION_PATCHLEVEL 19; echo \#define LINUX_VERSION_SUBLEVEL 0; } > include/generated/uapi/linux/.version.h.tmp; if [ ! -r include/generated/uapi/linux/version.h ] || ! cmp -s include/generated/uapi/linux/version.h include/generated/uapi/linux/.version.h.tmp; then : '  UPD     include/generated/uapi/linux/version.h'; mv -f include/generated/uapi/linux/.version.h.tmp include/generated/uapi/linux/version.h; fi
/home/rmk/git/linux-rmk/scripts/remove-stale-files
make -f /home/rmk/git/linux-rmk/scripts/Makefile.build obj=scripts/dtc
make -f /home/rmk/git/linux-rmk/scripts/Makefile.asm-generic obj=arch/arm/include/generated/asm \
generic=include/asm-generic
make -f /home/rmk/git/linux-rmk/scripts/Makefile.build obj=scripts
set -e; mkdir -p include/generated/; trap "rm -f include/generated/.utsrelease.h.tmp" EXIT; {   if [ `echo -n "5.19.0+" | wc -c ` -gt 64 ]; then echo '"5.19.0+" exceeds 64 characters' >&2; exit 1; fi; echo \#define UTS_RELEASE \"5.19.0+\"; } > include/generated/.utsrelease.h.tmp; if [ ! -r include/generated/utsrelease.h ] || ! cmp -s include/generated/utsrelease.h include/generated/.utsrelease.h.tmp; then : '  UPD     include/generated/utsrelease.h'; mv -f include/generated/.utsrelease.h.tmp include/generated/utsrelease.h; fi
make -f /home/rmk/git/linux-rmk/scripts/Makefile.build obj=arch/arm/tools kapi
make -f /home/rmk/git/linux-rmk/scripts/Makefile.build obj=scripts/mod
set -e; mkdir -p scripts/mod/; trap "rm -f scripts/mod/.devicetable-offsets.h.tmp" EXIT; {       echo "#ifndef __DEVICETABLE_OFFSETS_H__"; echo "#define __DEVICETABLE_OFFSETS_H__"; echo "/*"; echo " * DO NOT MODIFY."; echo " *"; echo " * This file was generated by Kbuild"; echo " */"; echo ""; sed -ne  's:^[[:space:]]*\.ascii[[:space:]]*"\(.*\)".*:\1:; /^->/{s:->#\(.*\):/* \1 */:; s:^->\([^ ]*\) [\$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}' < scripts/mod/devicetable-offsets.s; echo ""; echo "#endif"; } > scripts/mod/.devicetable-offsets.h.tmp; if [ ! -r scripts/mod/devicetable-offsets.h ] || ! cmp -s scripts/mod/devicetable-offsets.h scripts/mod/.devicetable-offsets.h.tmp; then : '  UPD     scripts/mod/devicetable-offsets.h'; mv -f scripts/mod/.devicetable-offsets.h.tmp scripts/mod/devicetable-offsets.h; fi
make -f /home/rmk/git/linux-rmk/scripts/Makefile.build obj=.
set -e; mkdir -p include/generated/; trap "rm -f include/generated/.bounds.h.tmp" EXIT; {        echo "#ifndef __LINUX_BOUNDS_H__"; echo "#define __LINUX_BOUNDS_H__"; echo "/*"; echo " * DO NOT MODIFY."; echo " *"; echo " * This file was generated by Kbuild"; echo " */"; echo ""; sed -ne        's:^[[:space:]]*\.ascii[[:space:]]*"\(.*\)".*:\1:; /^->/{s:->#\(.*\):/* \1 */:; s:^->\([^ ]*\) [\$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}' < kernel/bounds.s; echo ""; echo "#endif"; } > include/generated/.bounds.h.tmp; if [ ! -r include/generated/bounds.h ] || ! cmp -s include/generated/bounds.h include/generated/.bounds.h.tmp; then : '  UPD     include/generated/bounds.h'; mv -f include/generated/.bounds.h.tmp include/generated/bounds.h; fi
set -e; mkdir -p include/generated/; trap "rm -f include/generated/.timeconst.h.tmp" EXIT; { echo 250 | bc -q /home/rmk/git/linux-rmk/kernel/time/timeconst.bc; } > include/generated/.timeconst.h.tmp; if [ ! -r include/generated/timeconst.h ] || ! cmp -s include/generated/timeconst.h include/generated/.timeconst.h.tmp; then : '  UPD     include/generated/timeconst.h'; mv -f include/generated/.timeconst.h.tmp include/generated/timeconst.h; fi
  sh /home/rmk/git/linux-rmk/scripts/atomic/check-atomics.sh
set -e; mkdir -p include/generated/; trap "rm -f include/generated/.asm-offsets.h.tmp" EXIT; {   echo "#ifndef __ASM_OFFSETS_H__"; echo "#define __ASM_OFFSETS_H__"; echo "/*"; echo " * DO NOT MODIFY."; echo " *"; echo " * This file was generated by Kbuild"; echo " */"; echo ""; sed -ne  's:^[[:space:]]*\.ascii[[:space:]]*"\(.*\)".*:\1:; /^->/{s:->#\(.*\):/* \1 */:; s:^->\([^ ]*\) [\$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}' < arch/arm/kernel/asm-offsets.s; echo ""; echo "#endif"; } > include/generated/.asm-offsets.h.tmp; if [ ! -r include/generated/asm-offsets.h ] || ! cmp -s include/generated/asm-offsets.h include/generated/.asm-offsets.h.tmp; then : '  UPD     include/generated/asm-offsets.h'; mv -f include/generated/.asm-offsets.h.tmp include/generated/asm-offsets.h; fi
  sh /home/rmk/git/linux-rmk/scripts/checksyscalls.sh arm-linux-gnueabihf-gcc -Wp,-MMD,./.missing-syscalls.d -nostdinc -I/home/rmk/git/linux-rmk/arch/arm/include -I./arch/arm/include/generated -I/home/rmk/git/linux-rmk/include -I./include -I/home/rmk/git/linux-rmk/arch/arm/include/uapi -I./arch/arm/include/generated/uapi -I/home/rmk/git/linux-rmk/include/uapi -I./include/generated/uapi -include /home/rmk/git/linux-rmk/include/linux/compiler-version.h -include /home/rmk/git/linux-rmk/include/linux/kconfig.h -include /home/rmk/git/linux-rmk/include/linux/compiler_types.h -D__KERNEL__ -mlittle-endian -fmacro-prefix-map=/home/rmk/git/linux-rmk/= -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Werror=return-type -Wno-format-security -std=gnu11 -fno-dwarf2-cfi-asm -fno-ipa-sra -mabi=aapcs-linux -mfpu=vfp -funwind-tables -mtp=cp15 -marm -Wa,-mno-warn-deprecated -D__LINUX_ARM_ARCH__=7 -march=armv7-a -msoft-float -Uarm -fno-delete-null-pointer-checks -Wno-frame-address -Wno-format-truncation -Wno-format-overflow -Wno-address-of-packed-member -O2 -fno-allow-store-data-races -Wframe-larger-than=1024 -fno-stack-protector -Wimplicit-fallthrough=5 -Wno-main -Wno-unused-but-set-variable -Wno-unused-const-variable -fomit-frame-pointer -fno-stack-clash-protection -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -Wcast-function-type -Wno-stringop-truncation -Wno-stringop-overflow -Wno-restrict -Wno-maybe-uninitialized -Wno-alloc-size-larger-than -fno-strict-overflow -fno-stack-check -fconserve-stack -Werror=date-time -Werror=incompatible-pointer-types -Werror=designated-init -Wno-packed-not-aligned -I /home/rmk/git/linux-rmk/. -I ./.    -DKBUILD_MODFILE='"./missing-syscalls"' -DKBUILD_BASENAME='"missing_syscalls"' -DKBUILD_MODNAME='"missing_syscalls"' -D__KBUILD_MODNAME=kmod_missing_syscalls
make -f /home/rmk/git/linux-rmk/scripts/Makefile.build obj=arch/arm \
single-build=1 \
need-builtin=1 need-modorder=1
make -f /home/rmk/git/linux-rmk/scripts/Makefile.build obj=arch/arm/lib \
single-build=1 \
need-builtin=1 need-modorder=1
make -f /dev/null arch/arm/lib/findbit.o
make[3]: *** No rule to make target 'arch/arm/lib/findbit.o'.  Stop.
make[2]: *** [/home/rmk/git/linux-rmk/scripts/Makefile.build:441: __build] Error 2
make[1]: *** [/home/rmk/git/linux-rmk/Makefile:1843: arch/arm] Error 2
make[1]: *** Waiting for unfinished jobs....
  arm-linux-gnueabihf-gcc -Wp,-MMD,arch/arm/lib/.findbit.o.d -nostdinc -I/home/rmk/git/linux-rmk/arch/arm/include -I./arch/arm/include/generated -I/home/rmk/git/linux-rmk/include -I./include -I/home/rmk/git/linux-rmk/arch/arm/include/uapi -I./arch/arm/include/generated/uapi -I/home/rmk/git/linux-rmk/include/uapi -I./include/generated/uapi -include /home/rmk/git/linux-rmk/include/linux/compiler-version.h -include /home/rmk/git/linux-rmk/include/linux/kconfig.h -D__KERNEL__ -mlittle-endian -fmacro-prefix-map=/home/rmk/git/linux-rmk/= -D__ASSEMBLY__ -fno-PIE -mabi=aapcs-linux -mfpu=vfp -funwind-tables -mtp=cp15 -marm -Wa,-mno-warn-deprecated -D__LINUX_ARM_ARCH__=7 -march=armv7-a -include asm/unified.h -msoft-float -I /home/rmk/git/linux-rmk/arch/arm/lib -I ./arch/arm/lib    -c -o arch/arm/lib/findbit.o /home/rmk/git/linux-rmk/arch/arm/lib/findbit.S
  /home/rmk/git/linux-rmk/scripts/check-local-export arch/arm/lib/findbit.o
make[1]: Leaving directory '/home/rmk/git/build/multi'
make: *** [Makefile:219: __sub-make] Error 2

Clearly, kbuild knows how to do this, because it issued the appropriate
command to create the object file!

If I don't use -j2, then make fails at the error without building
findbit.o.

Mike Rapport reports similar issues to me, so it seems it's not just me
encountering this problem.

Any ideas why the kbuild infrastructure thinks it can't build a .o from
a .S file?

Thanks.

-- 
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