Saturday, November 26, 2011

FreeBSD on the TP-Link TL-WR1043nd!

I've now included (almost) all of the support needed to run FreeBSD natively on the TP-Link TL-WR1043nd. It's a 3-antenna, 2x2 stream 2.4ghz 802.11n AP which you can get for under AUD $100.

It supports hostap mode (which is what I bet most of you want to use) and I'm currently using it at home alongside my Ubiquiti Routerstation Pro based hostap (which is what I use to test out all the other pre-11n and 11n NICs that I currently own.)

I currently get around 50mbit TCP throughput - but I leave full FreeBSD-HEAD debugging on. I'm sure I can push the unit closer to 100mbit. (Compare to the Routerstation Pro + AR9160 hostap - where I routinely get 160mbit of TCP throughput.)

What works (read: what I've tested):
  • Ethernet (at least the WAN port);
  • Wireless - 802.11bgn - 20/40mhz operation as well as legacy operation (and both, if that's what you need);
  • Serial console - if you've soldered in one.

The firmware image stores the configuration in a 64k flash partition which is read upon boot. You can modify files in /etc and then save these to flash via "cfg_save".

What isn't supported:
  • The onboard switch - so I believe the only port available at the present moment is the WLAN port;
  • The GPIO lines aren't being configured, so the WLAN, status and USB/QSS buttons don't function.
I haven't tested out Multi-SSID mode yet. The earlier AR9130 revisions have some issues with multi-SSID mode and handling block-ack tracking, so I _think_ I'll need to somehow disable aggregation on the second and later VAP interfaces. Just keep that in mind if you're tinkering.

Further details about the hardware and how to build the software for yourself can be found here in my FreeBSD wifi development project wiki.

No, I won't (yet) be putting up firmware images for people to test. Things are changing quite rapidly and there's no easy way to reflash a unit once you've placed FreeBSD on it - you'll need to have added a serial console to the device.

FreeBSD 802.11n update: 27 November 2011.

I've merged in most of the reset related fixes from my git tree into FreeBSD-HEAD. This means that normal resets (eg stuck beacon, calibration resets, etc) shouldn't drop frames any longer.

Frames are still dropped during things like channel/operation mode changes and channel scanning (which does do a channel change.) I'll have to look into that at a later stage. If you're using this in station mode you will likely need to disable background scanning or your aggregation sessions may occasionally drop. You'll have random messages logged when frames are dropping during a flush or reset, so just check your system dmesg log for anything from the ath driver.

I'll be next working on correctly handling failed/filtered frames and then adding some transition stuff to net80211 so the TIM/ATIM bitmaps can be kept correctly up to date. This should fix some of the power saving issues that I'm sure exist.

Unfortunately transmitting BAR frames is still quite a bit off. There's a lot more tidying up that I'd like to do before I start down the path of handling BAR TX, including trying to figure out how to better handle packet transmission and reception when the NIC is off-channel (eg when doing a background channel scan.)

I also have a long list of things I'd like to do to the rate control code and all the surrounding code which sets up rates and creates aggregates. The code I ported/wrote is a little too verbose and duplicate-y for me. That likely will occur after the christmas break.


Wednesday, November 16, 2011

FreeBSD is now doing (even more) 802.11n..

I held off merging in my 802.11n work as much as possible but I decided that I'd like to get it done before the end of the year. Even though 9.0-RELEASE is still around the corner, I decided that it would be better to merge in what I have into -HEAD and then tidy that up then wait for what could be a few more months.

So, it's in there, bugs and all, supporting both station and hostap mode. No, wds, adhoc, mesh and TDMA aren't currently supported (I have enough bugs to worry about for the time being, without trying to debug the other operating modes. But I'd like to.)

What works:
  • TX and RX aggregation!
  • The rest of the 802.11n negotiation stuff, mostly thanks to Bernhard Schmidt who fixed up a lot of the net80211 quirks.
  • Lots of ANI changes which hopefully make noisy environments more stable.

What doesn't yet work:

  • Interface resets cause frames to be dropped from the RX and TX queues. This messes up aggregation and causes sessions to hang. I'm fixing that up in a git branch at the moment.
  • BAR TX - I'll implement BAR TX soon - it's just tricky to get right.
  • Filtered frames - ie, TX failed frames from the hardware. Instead of the current method of "always try", the hardware supports failing the current and subsequent frames in a set. That way a hostap seeing a station going into power saving mode can quickly abort all TX frames to said station and then only retransmit them when the station indicates it's again awake. If I don't do this then the hardware will constantly fail a lot of frames, causing BAR frames to be TXed when they likely shouldn't be.

But it's enough to try. So if you have an AR5416, AR9160, AR9220, AR9280, AR9285, AR9227 or AR9287, give it a whirl. If you have a pre-11n NIC then please, give it a go too. I'd like to ensure that the hardware support for earlier chipsets hasn't broken.

If you'd like to use this in production on a hostap then please keep in mind that power saving support isn't entirely functional and featured, so stations which go into frequent power saving mode may have some performance issues. I'll tinker with this some more soon.

Finally, thank you very much to Hobnob, Inc. for sponsoring this work and Qualcomm Atheros for providing me source code, documentation and assistance in understanding how all of this works.