[Users] Template: Kernel too old

[Kir Kolyshkin]

On 10/03/2013 02:10 PM, Michel Käser wrote:
> Hi again (and sorry for creating new top-level threads all the
> time...but I didn't manage to do it correct until now).
>
> Let me quickly summarize the whole process a little bit more in detail:
>
> 1. I created a Mageia 3 template based on their current release
> 2. I packed it for OpenVZ and created a container using the template
> 3. Starting the template gives the error "Kernel too old"
> 4. Trying to manually chroot into the VE directory also gives "Kernel
> too old"
> 5. I then tried adding a line in osrelease.conf to fake a newer kernel
> (mageia-3 3.8.13)
> 6. Starting the VE with --verbose shows that the osrelease.conf line is
> applied - but the same error appears: "Kernel too old"
>
> I then did some research in the Mageia IRC to get the oldest supported
> kernel and they advised me to upgrade the "glibc" package to their
> testing repository as they "downgraded" the kernel requirement there.
> After this, the template works (also manually chrooting).
>
> While this confirms there was a kernel requirement issue, it still seems
> like a bug to me in vzctl. Why? Because adding the template to
> osrelease.conf should fix this. I understand that this doesn't fix
> manually chrooting (as vzctl isn't applied then) - but it should fix the
> start of the VE through vzctl.
>
> You can download the "broken" template here if you'd like to dig deeper:
> https://www.dropbox.com/s/jnst0lcieaf9neg/mageia-3-x86_64.tar.gz
>

OK I went deep and wide and found out that modern glibc
tries to figure out the kernel version without using uname()
or reading /proc/sys/kernel/osrelease, but by analysing vdso
(a memory segment provided by the kernel). And this is where
we don't change kernel version apparently.

I filed a kernel bug for that, you can read it for some more info
and/or add yourself to Cc list: https://bugzilla.openvz.org/2768

Regards,
   Kir.