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Message-ID: <CAK7LNARe25AX6gLxHaSb3YANcx=10WW0cisKUnZY-mWFAUiGow@mail.gmail.com> Date: Tue, 21 Jul 2015 15:58:00 +0900 From: Masahiro Yamada <yamada.masahiro@...ionext.com> To: Russell King - ARM Linux <linux@....linux.org.uk> Cc: linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>, Michal Marek <mmarek@...e.cz>, Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] ARM: add boot image dependencies not to generate invalid images Hi Russel, No more comment? I answered your question. 2015-07-11 1:41 GMT+09:00 Masahiro Yamada <yamada.masahiro@...ionext.com>: > Hi Russel, > > > 2015-07-10 19:22 GMT+09:00 Russell King - ARM Linux <linux@....linux.org.uk>: >> On Mon, Jul 06, 2015 at 09:37:04PM +0900, Masahiro Yamada wrote: >>> [3] Then, re-build "all" and "uImage" simultaneously. >>> You will get an invalid uImage at random. >>> $ make -s -j8 ARCH=arm UIMAGE_LOADADDR=0x80208000 all uImage >>> Image Name: Linux-4.2.0-rc1-00008-g1c4c715-d >>> Created: Mon Jul 6 17:52:22 2015 >>> Image Type: ARM Linux Kernel Image (uncompressed) >>> Data Size: 26768 Bytes = 26.14 kB = 0.03 MB >>> Load Address: 80208000 >>> Entry Point: 80208000 >> >> At no point in the above do I see an attempt to rebuild init/main.o, >> which there should be as you touched the corresponding .c file - >> because you're hiding that output with -s. Please show what's going >> on without using -s. > > Please see the log attached at the end of this message. > > >>> "make uImage" could descend into arch/arm/boot/Makefile before >>> "make zImage" is completed because arch/arm/Makefile describes no >>> dependency among boot targets. >> >> The uImage target should depend on vmlinux, which should force the >> rebuild of init/main.o, and relink of the top-level vmlinux file >> before decending into arch/arm/boot/Makefile for the >> arch/arm/boot/uImage target. >> >> That makefile contains the dependencies required to order things >> correctly - the arch/arm/boot/uImage target depends on >> arch/arm/boot/zImage, which in turn depends on >> arch/arm/boot/compressed/vmlinux, and then arch/arm/boot/Image. >> >> In other words, arch/arm/boot/Makefile deals with the dependencies >> between the targets it's responsible for building itself. > > No, you do not understand what is happening in here. > > > The dependencies among targets such as Image, zImage, uImage, > are fully described in arch/arm/boot/Makefile, but it is not enough. > > Because arch/arm/boot/Makefile is _not_ included from the top-level Makefile, > the top-level build cannot know the dependency between zImage and uImage. > > arch/arm/Makefile, which is included from the top Makefile, > only describes that zImage depends on vmlinux, > and uImage depends on vmlinux as well. > But, no dependency between zImage and uImage is written in arch/arm/Makefile. > > Consequently, we run make with the parallel option, first Kbuild > updates vmlinux, > and then two different threads descends into arch/arm/boot/Makefile > almost at the same time, one for updating zImage and the other for uImage. > > The is a race between the two threads. > > While one thread is re-generating zImage and also uImage on top of that, > the other thread tries to re-generate zImage independently. > > zImage is overwritten by the slower thread, and then uImage is > re-generated based on the broken zImage. > > See my detailed build log below: > > Please note: > "Kernel: arch/arm/boot/zImage is ready" > is displayed twice, > the first one is shown before the uImage log, and the second one is > after uImage. > > zImage is correct, but uImage is extremely small when this problem happens. > > > > $ git describe > v4.2-rc1-62-gc4b5fd3 > > > $ touch init/main.c > $ 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 > GZIP arch/arm/boot/compressed/piggy.gzip > LD arch/arm/boot/compressed/vmlinux > OBJCOPY arch/arm/boot/zImage > Kernel: arch/arm/boot/zImage is ready > UIMAGE arch/arm/boot/uImage > Image Name: Linux-4.2.0-rc1-00062-gc4b5fd3-d > Created: Sat Jul 11 01:22:22 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 > $ LANG=C ls -l arch/arm/boot/ > total 19636 > -rwxrwxr-x 1 masahiro masahiro 13766656 Jul 11 01:22 Image > -rw-rw-r-- 1 masahiro masahiro 3137 Jul 3 01:17 Makefile > drwxrwxr-x 2 masahiro masahiro 4096 Jul 3 01:17 bootp > drwxrwxr-x 2 masahiro masahiro 4096 Jul 11 01:22 compressed > drwxrwxr-x 3 masahiro masahiro 155648 Jul 11 00:58 dts > -rw-rw-r-- 1 masahiro masahiro 1648 Jul 3 01:17 install.sh > -rw-rw-r-- 1 masahiro masahiro 26536 Jul 11 01:22 uImage > -rwxrwxr-x 1 masahiro masahiro 6135048 Jul 11 01:22 zImage > > > > > > > > -- > Best Regards > Masahiro Yamada -- Best Regards Masahiro Yamada -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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