Hi, I've been investigating an issue in Ubuntu [1] which nominally relates to sysctl. After analysing the problem [2], it appears that the real problem is that although modprobe allows a modules _module parameters_ to be set at load time, it does not provide a way to set a modules sysfs _kernel parameters_ at load time.
So, modules that specify kernel parameters but *not* module parameters, such as the 'bridge' module, do not get the correct values set when modprobe loads. The reason is that in Ubuntu we run 'sysctl -ep' as early as possible (for options like kernel.printk). Any settings in /etc/sysctl.* relating to modules that haven't yet been loaded cannot of course be applied. Later, the bridge module is loaded via modprobe. However, the bridges fail to start since their settings are incorrect (as the required settings are in /etc/sysctl.*, but sysctl has now finished). One possible solution to the problem would be to mandate that all modules which have configurable kernel parameters also provide equivalent module parameters to allow those values to be set at load time. Another possible solution might be for modprobe to extract the relevant bits from sysctl and apply them somehow(?) The approach adopted for Ubuntu currently is to simply call sysctl *twice* - once as early as possible, and again after all network interfaces are up. This seems like the best we can do currently, but it isn't perfect since it only fixes the problem for network devices. I'd be interested in your thoughts on a holistic solution to this issue. Kind regards, James. [1] - https://bugs.launchpad.net/ubuntu/+source/procps/+bug/771372 [2] - https://bugs.launchpad.net/ubuntu/+source/procps/+bug/771372/comments/4 -- James Hunt ____________________________________ -- To unsubscribe from this list: send the line "unsubscribe linux-modules" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
