Messages in this thread Patch in this message | | | From | Yifan Hong <> | Date | Mon, 24 Apr 2023 11:32:59 -0700 | Subject | Re: [PATCH v2] kheaders: Follow symlinks to source files. |
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On Sun, Apr 23, 2023 at 4:53 AM Masahiro Yamada <masahiroy@kernel.org> wrote: > > On Thu, Apr 20, 2023 at 10:01 AM Yifan Hong <elsk@google.com> wrote: > > > > When the kernel is built inside a sandbox container, > > a forest of symlinks to the source files may be > > created in the container. In this case, the generated > > kheaders.tar.xz should follow these symlinks > > to access the source files, instead of packing > > the symlinks themselves. > > > > Signed-off-by: Yifan Hong <elsk@google.com> > > Reviewed-by: Matthias Maennich <maennich@google.com> > > > > Please teach me how to reproduce your problem.
Thanks for your reply. When I say "container", I mean a forest of symlinks that point to the original source files. Here are the steps I do to mimic the sandbox that the container program creates.
On an x86 machine, I have a linux tree checkout at /mnt/sdb/linux, and an empty directory at /mnt/sdb/linux2. Then I **created this fake sandbox** in /mnt/sdb/linux2 by doing: ``` $ cd /mnt/sdb/linux $ find . -type d -exec mkdir -p /mnt/sdb/linux2/{} \; $ find . -type f -exec ln -sf /mnt/sdb/linux/{} /mnt/sdb/linux2/{} \; ```
Then, I cross compile an arm64 kernel with tinyconfig. Here are the steps I take: ``` export ARCH=arm64 export SUBARCH=arm export CROSS_COMPILE=/home/elsk/toolchains/aarch64--glibc--stable-2022.08-1/bin/aarch64-linux- # downloaded from https://toolchains.bootlin.com/ make tinyconfig; make menuconfig # then select CONFIG_SYSFS and CONFIG_IKHEADERS make -j64 ```
This will show that kheaders_data.tar.xz contains the symlinks, e.g. in my case: ``` $ tar tvf ./kernel/kheaders_data.tar.xz | head [...] lrwxrwxrwx 0/0 0 2023-04-24 11:19 ./arch/arm64/include/asm/acenv.h -> /mnt/sdb/linux/./arch/arm64/include/asm/acenv.h ```
However, the issue for me is that these symlinks are no longer useful under sysfs when I am booting the kernel on the target arm64 machine, because it is a different machine (arm64) than the machine (x86) where I compiled this kernel.
> > > > I built the kernel inside a container, > but I do not see any difference. > > > > We have some symbolic links in include/, > but those reference relative paths. > How building the kernel in a container > makes a difference?
Please see above; the container contains a forest of symlinks pointing to the original source tree. Then `make` is executed in that container directory.
> > > masahiro@bc5c2c958b53:/tmp/foo$ tar Jxf kheaders_data.tar.xz > masahiro@bc5c2c958b53:/tmp/foo$ find . -type l > ./include/dt-bindings/clock/qcom,dispcc-sm8350.h > ./include/dt-bindings/clock/qcom,dispcc-sm8150.h > ./include/dt-bindings/input/linux-event-codes.h > masahiro@bc5c2c958b53:/tmp/foo$ find . -type l | xargs ls -l > lrwxrwxrwx 1 masahiro masahiro 20 Apr 23 11:47 > ./include/dt-bindings/clock/qcom,dispcc-sm8150.h -> > qcom,dispcc-sm8250.h > lrwxrwxrwx 1 masahiro masahiro 20 Apr 23 11:47 > ./include/dt-bindings/clock/qcom,dispcc-sm8350.h -> > qcom,dispcc-sm8250.h > lrwxrwxrwx 1 masahiro masahiro 36 Apr 23 11:47 > ./include/dt-bindings/input/linux-event-codes.h -> > ../../uapi/linux/input-event-codes.h > > > > > > > > > > > > > > --- > > kernel/gen_kheaders.sh | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/gen_kheaders.sh b/kernel/gen_kheaders.sh > > index 1ef9a87511f5..70a75a9a7535 100755 > > --- a/kernel/gen_kheaders.sh > > +++ b/kernel/gen_kheaders.sh > > @@ -87,7 +87,7 @@ find $cpio_dir -type f -print0 | > > # pre-sorted, as --sort=name might not be available. > > find $cpio_dir -printf "./%P\n" | LC_ALL=C sort | \ > > tar "${KBUILD_BUILD_TIMESTAMP:+--mtime=$KBUILD_BUILD_TIMESTAMP}" \ > > - --owner=0 --group=0 --numeric-owner --no-recursion \ > > + --owner=0 --group=0 --numeric-owner --no-recursion --dereference \ > > -I $XZ -cf $tarfile -C $cpio_dir/ -T - > /dev/null > > > > echo $headers_md5 > kernel/kheaders.md5 > > -- > > 2.40.0.634.g4ca3ef3211-goog > > > > > -- > Best Regards > Masahiro Yamada > > -- > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com. >
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