I am seeing something really weird inside a chroot-ed Debian
But first, a bit of backstory... This is long, but the question is complex and any potential help depends on knowing the full story.
I have an embedded ARM SoC that runs Linux - more specifically,
armel Lenny on a 2.6.17 kernel. The Debian distro itself is
easily upgradeable to later versions (
sudo apt-get dist-upgrade)
and can thus be brought up to speed, to the
armel versions of
squeeze or even
The problem is that the kernel is a custom one... The ARM SoC in question is not part of the mainline kernel, so it is pretty much abandoned at 2.6.17.
If you know how Linux and GLIBC work, you can already see the problem - GLIBC versions are compiled with a minimum supported kernel version... Which has moved way past 2.6.17. So if we try to e.g. chroot to a Debian squeeze...
$ # From inside the little ARM machine running Debian Lenny $ sudo debootstrap --arch armel squeeze /squeeze \ http://ftp.whateverCountry.debian.org/debian $ sudo -i # mount -t proc none /squeeze/proc # mount -t sysfs none /squeeze/sys # mount -t devpts none /squeeze/dev/pts # chroot /squeeze Fatal: Kernel too old
...we see a message from the GLIBC of
squeeze, telling us that
it was not compiled to work with this old kernel (2.6.17).
The same problem happens with wheezy, too - since it is newer than squeeze - and will in fact happen with any Debian version from now on, since their GLIBC won't work on my 2.6.17 kernel.
At first I thought this was a deal breaker - but then I realized that I can in theory recompile GLIBC to work with the older kernel my SoC is using... But I'd need an identical environment to what was used to build the libc6 package in e.g. Debian squeeze.
I am guessing the compilation of GLIBC and the preparation of the libc6_2.11.3-4.deb file is done via automated cross-compiling machinery invented by the Gods of Debian.
I am no God... nor could I find anything in Google about how
to become one - i.e. how to use my Core i5 as a host, to
cross-compile GLIBC using the exact same settings that the packaged
version (inside Debian
squeeze) is using.
So I tricked it - I figured out how to setup the ARM version
of Debian squeeze on my Core i5 (a technique that uses a static
version of the
Once I chrooted in my x86-hosted version of
I was able to simply...
$ cd /var/tmp $ apt-get source libc6 ... $ # edit this in - compile for my kernel... $ vi eglibc-2.11.3/debian/sysdeps/linux.mk ... MIN_KERNEL_SUPPORTED := 2.6.17 ... $ export DEB_BUILD_OPTS="nocheck parallel=1" $ cd eglibc-2.11.3 $ dpkg-buildpackage -b -d -us -uc
...and after 3 hours (the Core i5-hosted chrooted version of
Debian-armel-squeeze is much slower than a native machine...)
I got my libc6 .deb package. It would probably take 3 months
to do this build in my SoC, so I am not complaining.
Going back inside my real ARM SoC, I copied all the libc files (.so) of the new package over the default ones of squeeze and tried to chroot...
# chroot squeeze/ root@ttsiodras:/#
Yes! It worked! (or so it seemed)
My custom libc reported from inside the chroot:
# /lib/libc.so.6 GNU C Library (Debian EGLIBC 2.11.3-4) stable release version 2.11.3, by Roland McGrath et al. Copyright (C) 2009 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Compiled by GNU CC version 4.4.5. Compiled on a Linux 2.6.26 system on 2014-10-23. Available extensions: crypt add-on version 2.1 by Michael Glad and others GNU Libidn by Simon Josefsson Native POSIX Threads Library by Ulrich Drepper et al Support for some architectures added on, not maintained in glibc core. BIND-8.2.3-T5B For bug reporting instructions, please see: <http://www.debian.org/Bugs/>.
Things seemed to work - I copied a file, invoked
But when I tried to use
apt-get to install some apps from
squeeze, I started getting... some unexpected errors:
# apt-get install indent Reading package lists... Done Building dependency tree... Done The following NEW packages will be installed: indent 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 110 kB of archives. After this operation, 516 kB of additional disk space will be used. Get:1 http://ftp.gr.debian.org/debian/ squeeze/main indent armel 2.2.11-1 [110 kB] Fetched 110 kB in 0s (236 kB/s) tar: ./control: Cannot utime: Function not implemented tar: ./md5sums: Cannot utime: Function not implemented tar: .: Cannot utime: Function not implemented tar: Exiting with failure status due to previous errors dpkg-deb: subprocess tar returned error exit status 2 dpkg: error processing /var/cache/apt/archives/indent_2.2.11-1_armel.deb (--unpack): subprocess dpkg-deb --control returned error exit status 2 configured to not write apport reports rm: cannot remove `/var/lib/dpkg/tmp.ci': Function not implemented dpkg: error while cleaning up: subprocess rm cleanup returned error exit status 1 Errors were encountered while processing: /var/cache/apt/archives/indent_2.2.11-1_armel.deb E: Sub-process /usr/bin/dpkg returned an error code (1)
Oh-oh... a bunch of
Function not implemented. That sounds like GLIBC reporting
that basic things are not working...
I managed to strace (don't ask how) and figured out that all the
renameat, etc - they are all reporting ENOSYS.
It appears that I was only partially successful - some system calls are failing in my new GLIBC.
Is it impossible to compile a
wheeze GLIBC to execute under 2.6.17?
Any ideas/pointers on what I did wrong and/or how to proceed would be much appreciated...