[PATCH] ARM: add boot image dependencies not to generate invalid images
Masahiro Yamada
yamada.masahiro at socionext.com
Sat Aug 8 05:29:58 PDT 2015
Hi Russell,
I will rephrase the git-description and post v2.
2015-07-21 15:58 GMT+09:00 Masahiro Yamada <yamada.masahiro at socionext.com>:
> Hi Russel,
>
> No more comment?
> I answered your question.
>
>
>
>
> 2015-07-11 1:41 GMT+09:00 Masahiro Yamada <yamada.masahiro at socionext.com>:
>> Hi Russel,
>>
>>
>> 2015-07-10 19:22 GMT+09:00 Russell King - ARM Linux <linux at arm.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
--
Best Regards
Masahiro Yamada
More information about the linux-arm-kernel
mailing list