aboutsummaryrefslogtreecommitdiff
path: root/arch/arm
diff options
context:
space:
mode:
authorMasahiro Yamada <yamada.masahiro@socionext.com>2015-08-17 04:03:33 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2015-08-18 13:59:59 +0100
commit3939f3345050b1ace675675c47d99fd7b606d9e3 (patch)
treecd291499390a590583ce379f55c98666e3dd22b8 /arch/arm
parent0f64b247e63ac8c214efa6725366b42563ab138c (diff)
downloadlinux-linaro-stable-3939f3345050b1ace675675c47d99fd7b606d9e3.tar.gz
ARM: 8418/1: add boot image dependencies to not generate invalid images
U-Boot is often used to boot the kernel on ARM boards, but uImage is not built by "make all", so we are often inclined to do "make all uImage" to generate DTBs, modules and uImage in a single command, but we should notice a pitfall behind it. In fact, "make all uImage" could generate an invalid uImage if it is run with the parallel option (-j). You can reproduce this problem with the following procedure: [1] First, build "all" and "uImage" separately. You will get a valid uImage $ git clean -f -x -d $ export CROSS_COMPILE=<your-tools-prefix> $ make -s -j8 ARCH=arm multi_v7_defconfig $ make -s -j8 ARCH=arm all $ make -j8 ARCH=arm UIMAGE_LOADADDR=0x80208000 uImage CHK include/config/kernel.release CHK include/generated/uapi/linux/version.h CHK include/generated/utsrelease.h make[1]: `include/generated/mach-types.h' is up to date. CHK include/generated/timeconst.h CHK include/generated/bounds.h CHK include/generated/asm-offsets.h CALL scripts/checksyscalls.sh CHK include/generated/compile.h Kernel: arch/arm/boot/Image is ready Kernel: arch/arm/boot/zImage is ready UIMAGE arch/arm/boot/uImage Image Name: Linux-4.2.0-rc5-00156-gdd2384a-d Created: Sat Aug 8 23:21:35 2015 Image Type: ARM Linux Kernel Image (uncompressed) Data Size: 6138648 Bytes = 5994.77 kB = 5.85 MB Load Address: 80208000 Entry Point: 80208000 Image arch/arm/boot/uImage is ready $ ls -l arch/arm/boot/*Image -rwxrwxr-x 1 masahiro masahiro 13766656 Aug 8 23:20 arch/arm/boot/Image -rw-rw-r-- 1 masahiro masahiro 6138712 Aug 8 23:21 arch/arm/boot/uImage -rwxrwxr-x 1 masahiro masahiro 6138648 Aug 8 23:20 arch/arm/boot/zImage [2] Update some source file(s) $ touch init/main.c [3] Then, re-build "all" and "uImage" simultaneously. You will get an invalid uImage at random. $ make -j8 ARCH=arm UIMAGE_LOADADDR=0x80208000 all uImage CHK include/config/kernel.release CHK include/generated/uapi/linux/version.h CHK include/generated/utsrelease.h make[1]: `include/generated/mach-types.h' is up to date. CHK include/generated/timeconst.h CHK include/generated/bounds.h CHK include/generated/asm-offsets.h CALL scripts/checksyscalls.sh CC init/main.o CHK include/generated/compile.h LD init/built-in.o LINK vmlinux LD vmlinux.o MODPOST vmlinux.o GEN .version CHK include/generated/compile.h UPD include/generated/compile.h CC init/version.o LD init/built-in.o KSYM .tmp_kallsyms1.o KSYM .tmp_kallsyms2.o LD vmlinux SORTEX vmlinux SYSMAP System.map OBJCOPY arch/arm/boot/Image Building modules, stage 2. Kernel: arch/arm/boot/Image is ready GZIP arch/arm/boot/compressed/piggy.gzip AS arch/arm/boot/compressed/piggy.gzip.o Kernel: arch/arm/boot/Image is ready LD arch/arm/boot/compressed/vmlinux GZIP arch/arm/boot/compressed/piggy.gzip OBJCOPY arch/arm/boot/zImage Kernel: arch/arm/boot/zImage is ready UIMAGE arch/arm/boot/uImage Image Name: Linux-4.2.0-rc5-00156-gdd2384a-d Created: Sat Aug 8 23:23:14 2015 Image Type: ARM Linux Kernel Image (uncompressed) Data Size: 26472 Bytes = 25.85 kB = 0.03 MB Load Address: 80208000 Entry Point: 80208000 Image arch/arm/boot/uImage is ready MODPOST 192 modules AS arch/arm/boot/compressed/piggy.gzip.o LD arch/arm/boot/compressed/vmlinux OBJCOPY arch/arm/boot/zImage Kernel: arch/arm/boot/zImage is ready $ ls -l arch/arm/boot/*Image -rwxrwxr-x 1 masahiro masahiro 13766656 Aug 8 23:23 arch/arm/boot/Image -rw-rw-r-- 1 masahiro masahiro 26536 Aug 8 23:23 arch/arm/boot/uImage -rwxrwxr-x 1 masahiro masahiro 6138648 Aug 8 23:23 arch/arm/boot/zImage Please notice the uImage is extremely small when this issue is encountered. Besides, "Kernel: arch/arm/boot/zImage is ready" is displayed twice, before and after the uImage log. The root cause of this is the race condition between zImage and uImage. Actually, uImage depends on zImage, but the dependency between the two is only described in arch/arm/boot/Makefile. Because arch/arm/boot/Makefile is not included from the top-level Makefile, it cannot know the dependency between zImage and uImage. Consequently, when we run make with the parallel option, Kbuild updates vmlinux first, and then two different threads descends into the arch/arm/boot/Makefile almost at the same time, one for updating zImage and the other for uImage. While one thread is re-generating zImage, the other also tries to update zImage before creating uImage on top of that. zImage is overwritten by the slower thread and then uImage is created based on the half-written zImage. This is the reason why "Kernel: arch/arm/boot/zImage is ready" is displayed twice, and a broken uImage is created. The same problem could happen on bootpImage. This commit adds dependencies among Image, zImage, uImage, and bootpImage to arch/arm/Makefile, which is included from the top-level Makefile. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/Makefile3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 07ab3d203916..7451b447cc2d 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -312,6 +312,9 @@ INSTALL_TARGETS = zinstall uinstall install
PHONY += bzImage $(BOOT_TARGETS) $(INSTALL_TARGETS)
+bootpImage uImage: zImage
+zImage: Image
+
$(BOOT_TARGETS): vmlinux
$(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $(boot)/$@