Re: future of sysctls?
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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