Linux – Can new glibc versions be used with an old kernel

I made it :-)

I basically followed Gilles's advice and decided to do it properly: i.e. manage a complete cross-compilation of GLIBC. I started from crosstool-ng, and was initially disappointed - seeing that it didn't support my old kernel. I kept at it, though - manually editing the configuration file saved by crosstool-ng to do changes like these on the default arm-gnueabi build configuration:

$ ct-ng arm-unknown-linux-gnueabi
$ ct-ng menuconfig
...
$ vi .config
$ cat .config
...
CT_KERNEL_VERSION="2.6.17"
CT_KERNEL_V_2_6_17=y
CT_LIBC_VERSION="2.13"
CT_LIBC_GLIBC_V_2_13=y
CT_LIBC_GLIBC_MIN_KERNEL_VERSION="2.6.9"
CT_LIBC_GLIBC_MIN_KERNEL="2.6.9
...
$ ct-ng +libc

After numerous tests and failed attempts, the above changes did it - I got a compiled version of GLIBC that would work with my kernel, and copied the resulting files to my Debian Lenny ARM machine:

$ cd .build/arm-unknown-linux-gnueabi/build/build-libc-final/
$ tar zcpf newlibc.tgz $(find . -type f -iname \*.so)
$ scp newlibc.tgz root@mybook:.

I went all the way and moved past squeeze: I debootstrapped a /wheezy and then - very carefully - overwrote the GLIBC versions of the armel-debootstrapped /wheezy with my own:

# # In the ARM machine
# cd /wheezy/lib/arm-linux-gnueabi/
# mv /var/tmp/ohMyGod/libc.so libc-2.13.so
# mv /var/tmp/ohMyGod/rt/librt.so librt-2.13.so
...

...etc, making sure I didn't miss any shared libraries.

Finally, I copied over the ldd and ldconfig binaries (which were also part of GLIBC), and chrooted inside my /wheezy.

It worked.

I can only assume that the compilation of GLIBC from a chroot-ed 'qemu-arm' emulation inside a x86, somehow messed things up - maybe the configure process detects some stuff from the running environment - whereas the cross-compilation can't be misled.

So naturally I moved to the next step, and used a busybox-static shell to replace the {/bin,/sbin,...} folders of my old lenny with the wheezy ones - and rebooted into my brand new Wheezy :-)

I hereby claim that my WD MyBook World Edition is the only one on the planet running Debian Wheezy :-) If anyone else is interested, I can upload a tarball of the libc files someplace.