On 2013-06-07 7:05 PM, Simon Wunderlich wrote: > This is the follow up from the RFC posted a month ago. This patchset adds generic > channel switch support for AP. This is required for DFS operation > (e.g. Wi-Fi Alliance requires this for 802.11h certification). This will also > be required for IBSS-DFS later. > > The rough design is: > * userspace asks kernel to switch a channel using the new NL80211_CMD_CHANNEL_SWITCH > command. It supplies IE information for the time while staying on the old channel and > announcing the switch, and IE information for after the switch to the new channel. > * IE information contains the beacon and optionally probe responses, which should > include (E)CSA IEs for the CSA case. Furthermore an offset is provided (for beacon > and probe response) to point to the counter field within the channel switch IEs. > * The driver gets the new beacons passed and must set them, and decrement the > counter field. When it reaches 0, the channel is changed and userspace notified. > > Discussion points: > * Assembling all these IE information is a little bit tedious but doable (I've > patched hostapd). > * Other future users like IBSS/MESH will not get the beacon/probe response IEs, as they > generate these beacons themselves. Therefore they need the COUNT attribute, which > is kind of duplicate right now. > * Userspace must generate/handle all IEs, which lifts the previous limitations of > the RFC (e.g. no change of band allowed, no operation mode change allowed). > * it currently works for me [TM] on my ath9k based machine I think this is a bit racy. Just because the driver gets a beacon from mac80211 doesn't mean that the beacon will be sent *immediately*. I'd recommend calling back from the driver into mac80211 on beacon tx completion. Also, it might make sense to skip CAB queue transmissions in this case. - Felix -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
