Re: future of sysctls?

[Lennart Poettering <lennart@poettering.net>]

On Thu, 12.05.11 17:41, Ludwig Nussel (ludwig.nussel@suse.de) wrote:

> Hi,
> 
> I'm currently struggling to find a sane way to set
> net.ipv6.conf.default.use_tempaddr.
> Traditionally at some point during boot "sysctl -e -q -p /etc/sysctl.conf" is
> called. That doesn't really work out anymore. The aforementioned setting needs
> to be applied after the ipv6 module is loaded (could be compiled into the
> kernel too though) otherwise it wouldn't apply. It needs to be set before a
> network driver is loaded though as the default value is copied to
> interfaces specific settings at interface creation time. On top of
> that there are also network interface specific sysctls that need to
> be applied after an interface is created (e.g.
> net.ipv6.conf.eth0.use_tempaddr).

Something like this is kinda broken anyway, since it is racy: you can
apply the sysctl only after the interface is already available.

Might be a good idea to just ignore these kinds of settings. Or if this
is not possible, then set them from NM or whatever controls the network.

> Are there any plans to better deal with that?
> Like e.g. emitting events when some part of the kernel registers a sysctl so
> userspace can override the compiled in default value?
> Or just offer sysfs attributes instead of sysctls?

In a systemd world the ipv6 module is loaded very early and hence the
sysctl should always be available, no special setup needed. If the same
problem appears in real life with other modules too, then we could order
sysctl setting after module loading and fix things by this.

Can't tell you though what to do in a non-systemd world however.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.