Re: future of sysctls?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


Lennart Poettering wrote:
> On Thu, 12.05.11 17:41, Ludwig Nussel (ludwig.nussel@xxxxxxx) wrote:
> > 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.

Exactly.

> 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.

That's that hack that's currently in place. Network scripts grep
/etc/sysctl.conf for interface specific settings...

> > 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.

Grepping for register_sysctl in the kernel sources shows quite a few modules
that use sysctls. A prominent one is nfs.
If you apply sysctl setttings after module loading, specifically network
drivers, the ipv6 setting won't have any effect anymore though.

cu
Ludwig

-- 
 (o_   Ludwig Nussel
 //\
 V_/_  http://www.suse.de/
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB 16746 (AG Nürnberg) 
--
To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Linux DVB]     [Video Technology]     [Asterisk]     [Photo]     [DCCP]     [Netdev]     [Xorg]     [Util Linux NG]     [Xfree86]     [Devices]     [Fedora Women]     [ALSA Devel]     [Linux USB]

Add to Google Powered by Linux