On Tue, 2009-12-01 at 20:19 -0500, Pavel Roskin wrote: > Anyway, I think that using module parameters for any configuration > creates a bad precedent. Disabling HT40 in the 2.4GHz band is a "fine > tuning" compared to other settings. But there may be many other such > "knobs" (e.g. ACK timeout), and if they all are controlled by mac80211 > parameters, it would be a maintenance nightmare. ACK timeout is a quite different knob. This particular setting is mostly required for some interoperability testing, but otherwise serves no real purpose since the AP can always disable 40 MHz anyway, and if it doesn't then it's very likely that somebody will use 40 MHz with the AP. In this case, the real solution to the interoperability problem would be using the frequency broker, but that can hardly be implemented in a reasonable time frame. However, the real problem lies with interoperability testing and certification with a system based around mac80211. In that case, the frequency broker does not help even if it were implemented. As such, I believe using a module parameter for a rarely used setting is a good trade-off, there's no real need to set this on the fly, but it does sometimes need to be set on boot (which is much easier to achieve this way) -- yet most of the time, apart from building complete systems based on the software, nobody cares. Now, you could make a point that it could be an out-of-tree patch for those systems that actually do require this type of interoperability testing and certification that requires this setting, but that is not very maintainable. > If module parameters are discourages for the drivers, mac80211 should > be held to the same standard. And I would argue that it is -- module parameters are still discouraged, that doesn't change with adding one. We currently have one in mac80211 to chose the rate control algorithm, but it too is a special case and ought to not be required. I don't see this parameter as configuration like ack timeout or 10mhz channels or ... I think this parameter solves a systems integration issue, not a configuration issue. johannes
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