On Tue, 2006-08-15 at 21:35 +0200, Michael Buesch wrote: > On Tuesday 15 August 2006 21:27, Simon Barber wrote: > > A further complication happens in Japan with 802.11j, and now in the USA > > too - with 802.11y in the 3.65Ghz band - here there are some new channel > > widths that are possible. Normally 802.11 is 20 or 22Mhz wide (20Mhz for > > OFDM modulations - 11a/g, 22 for 11b). In Japan's 4.9Ghz band you can > > run the OFDM at half rate, giving a 10Mhz wide channel, or at quarter > > rate, giving a 5Mhz wide channel. Hence same frequency, different > > channel spec. Using a channel number is the way to go. If we need > > something to convert between the 2 it should probably be a library in > > user space (in hostapd or wpa_supplicant) - hostapd does have this > > today. > > > > It might be nice if other applications could access this data too - but > > I don't think it needs to be inside the kernel. > > We need this conversion function, as most devices tune to frequencies, > not channels. So when a driver is instructed to tune to channel 2, > it must call back into the 80211 stack to ask for the frequency (based > on the current PHYMODE and the other parameters you mentioned above). > That call should IMO not result in a call to userspace. Userspace > should instead set flags _before_ in the stack and the conversion > callback would act on these flags. > That way userspace only has to tell the kernel once which frequency-band, > half, quater freq, or whatever it wants. The actual conversion > from channel number to freq (or the other way around) is trivial after > that, as it's only a few ifs and elses based on some cheap flags.
As long as there's a way for userspace to convert channel <-> frequency and back using the _same_ values as the driver is using, that's all I care about. I just don't want to have each userspace program have its own library of channel/frequency mappings simply because not enough information was exposed through the d80211 stack's API. Dan - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
