On Saturday 16 June 2007 11:51, Johannes Berg wrote: > On Sat, 2007-06-16 at 11:29 -0700, Michael Wu wrote: > > I think that decision was made without much consideration to the > > implementation details. > > I don't think the implementation details are much of a problem. It's > just a bit of message bouncing which is trivial. Except of course when > you consider wext, but hey, no need to consider that for this discussion > since you're proposing ditching wext completely. Not that I don't want > to ditch it, but people still use it and probably will. Heck, people > still use 'ifconfig'... > I'm not proposing to ditch wext completely. When did I say that? > > I thought it was a good idea then, but passing > > messages from userspace to the kernel and then to userspace again is > > really a waste of time. > > It's not happening a lot so it's not a waste of *much* time ;) > It's a waste of time when nl80211 needs to be patched every time we want an additional command in the userspace MLME. > > NetworkManager already uses wpa_supplicant to avoid all the > > nasty details of dealing with wireless configuration, so why not keep > > using it for everything instead of hiding wpa_supplicant behind nl80211? > > I hope that nm would start using nl80211 instead of talking to > wpa_supplicant and just start wpa_supplicant if necessary. Or maybe some > startup scripts start the userspace MLME (wpa_supplicant) for the > interfaces during boot/hotplug. > I don't think switching NM to nl80211 is reasonable unless you find someone to port all the legacy drivers to cfg80211 too. > > This is > > more simple and direct and allows the kernel to expose exactly what the > > hardware/kernel can do. Userspace won't have to change much and nl80211 > > won't have to support every possible thing a userspace MLME would want. > > It's not that the kernel will have to support everything that a > userspace MLME would want, but rather that the kernel needs to support > everything the MLME would want, to support fullmac drivers. > I don't think the needs of a firmware based MLME are necessarily the same as a userspace MLME. Some commands will certainly be the same, but just because the commands are there doesn't mean it's good to make them work if you have to fake it. The kernel should show what the hardware/stack can do and nothing more. > Another counter: when you have a tool like 'iw' that David wrote, then > it'll need to look for the userspace MLME every time you invoke it and > start communicating with it instead of the kernel. That's likely a waste > of much more time than just bouncing the messages. > I think the difference is trivial. Using nl80211 for what is effectively IPC seems very incorrect to me. -Michael Wu
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