On Tue, 2006-08-15 at 17:28 +0200, Johannes Berg wrote: > Hi, > > So I've thought about this all day long... After writing this mail I'll > go home and hope my inbox collects some feedback ;)
We might want to take the time to fix up a few of the ambiguities of WEXT that we've encountered over the past few years: o Separate attributes for signal strength units; signed integer type for dBm, unsigned integer type for RSSI. One 8-bit var to represent both is just too confusing for people, evidently (which is true...) o Merge functionality ENCODE and ENCODEEXT handlers into one o Separate attributes for channel and frequency o Method of finding out channel <-> frequency mapping (not all drivers support this in the SIOCGIWRANGE handler now) Nothing big here... but gives driver writers a much easier target to hit, and userspace app writers an easier API to understand. Dan > I've arrived at the following conclusions: > * we want to use genetlink > * we need an equivalent of the old commit() call, > but without all the stupidity > * we want to do packet injection and many other advanced > features with it, and keep it extensible > > NB: I have some code, so don't start ;) > > Hence, I came up with the following system. Note that I don't use any > private header for the netlink messages. > > - we implement a bunch of commands, for example NL80211_CMD_INJECT and > _SETATTR, _GETATTR[(attrnumber)] [easy with dumpit()], > _GETATTRGROUP, ... > > - we have a whole bunch of possible attributes: > NL80211_ATTR_FLAGS: flags for injecting a packet (e.g. want_notify) > NL80211_ATTR_IFINDEX: index of interface to use > (NL80211_ATTR_PHYIDX: (later) index of wiphy to configure) > NL80211_ATTR_ESSID, > FRAGTHRESHOLD, > CHANNEL,...: most of the old wext ioctls map to > attributes now > NL80211_ATTR_FRAME: frame to inject, or received mgmt frame > > - we use a few multicast groups: > (a) one for management frames that are received > (b) one for scan results as they come available > (When, for example, someone requests scan results, they are > simply multicast to the group+the requester, if they come > available during operation they can also be multicast here) > > Note that I haven't mentioned commit(). NL80211_CMD_GETATTRGROUP returns > a list of attributes that make sense to set with a single _SETATTR call > and multiple attributes. > > an old sequence of > iwconfig eth0 essid 'lalala' > iwconfig eth0 channel 2 > iwconfig eth0 commit > would then be translated in the compat layer to a single _SETATTR > message with the channel and essid attributes. Ultimately, we'll get rid > of this, so a userspace tool using the netlink configuration would just > tell the user via _GETATTRGROUP which attributes make sense to group > together for optimal card behaviour. > > As for the inject command, it looks like on the current wmgmt# interface > for d80211 has a bunch of implicit behaviour like looking into the > transmitted frame to see what type it is etc. I'd like to get rid of it > and stuff the information for that into ATTR_FLAGS instead. > > Oh and of course we'll have a structure somewhere that drivers and > stacks register with the module that provides this netlink interface. > That module will then also multiplex the commands to the drivers/stacks. > I have that mostly figured out. > > Since it will be easy to tell if a specific driver/stack implements > old-style wext or this new API we can allow drivers with both APIs to > coexist for a while. I won't map the new API to the old wext one of > course, but mapping the wext API to the new one we need anyway. Hence, > we can change the wext code to call the new API if present and the old > one otherwise (with a big fat printk), and then slowly migrate drivers > over. Due to the reduced commit logic, it should become simpler too, > even for old drivers. > > Anyway, comments appreciated. If we can agree on this general framework > I'll start implementing the groundwork and some of the rest for d80211 > soon. > > johannes > - > 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 - 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
