[Netkit.users] Issues with latest kernel : too old for filesystem's packages updates

Massimo Rimondini rimondin at dia.uniroma3.it
Fri Jun 14 11:47:24 CEST 2013

Hi Florian,

> Hi there !
> Recently, a few people recommended Netkit to me to help learn Linux networking and I started messing around with it.
> Since we are several here to wish to learn and experiment, I eventually thought about creating a collaborative set of labs to use on a central machine for more interactivity.
> However the version of Quagga included in Netkit's filesystem seems to be very old and lacks several features I'd have liked to use (eg. AS4) :(
> The website' FAQ clearly explains how to upgrade the existing Debian install or install new packages. However, the associated Netkit Kernel now seems to be too old...
> Since it is running off what seems to be a Debian Unstable snapshot from 2010, any newer package install post package update pulls in the newest glibc version 2.17.
> Since glibc 2.17, there is a minimum requirement for the Linux Kernel version of 2.6.16, according to their own changelog [ http://sourceware.org/ml/libc-announce/2012/msg00001.html ] -- which should be fine with Netkit's 2.6.22.
> However when attempting to update a running UML Machine, Debian complains about requiring a kernel newer than 2.6.32 and refuses to upgrade.
> Indeed, attempting to upgrade from a chroot environement (bypassing the kernel check since it matchs against the host' version) results in an unbootable filesystem (fails at init startup)...
> As such I'd like to ask the following questions :
>  - Are there any plans to update the provided kernel, or do anyone know where I can find a third-party one ?

We would like to provide updates (and likely will), but have been running a bit short on development power lately.
However, a very active contributor who has faced similar shortcomings to those you are reporting has already introduced many fixes and updates, most notably to the kernel and filesystem build systems. In case you need it, you may therefore consider rebuilding the kernel using his tools, available here: https://github.com/kartoch.

>  - Will Netkit run if building a newer kernel without the provided netkit patches ?

It should.

>  - If yes, to what extent could features be lost by the removal of those patches ? Will just any UML kernel run ?

Most notably, support for MPLS forwarding is dropped with a vanilla UML kernel. Some other basic functionalities like deterministic generation of MAC addresses for network interfaces and graceful virtual machine shutdown may also be lost.

>  - Last but not least, while only Debian is officially supported, is building a new filesystem from scratch from a different distro likely to succeed ?

It might succeeed, but would likely be much more complex due to the lack of appropriate tools for bootstrapping the distribution. Not to mention that many of the tweaks applied in the filesystem image of Netkit are Debian-specific.

> Thanks in advance ;)

You're welcome.


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