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zd1211rw

A large proportion of USB-wireless devices on the consumer market are based on the ZyDAS ZD1211. Several months after the acquisition, Atheros rebranded the chip to AR5007UG.

zd1211rw is a community effort to rewrite ZyDAS's ZD1211 driver. zd1211rw has been included in the kernel since Linux 2.6.18.

On January 11th 2006, a few developers announced a very early version of a rewritten driver, which had been under development for a few days. Soon after doing so, Ulrich Kunitz announced that he had already been working on a rewrite driver for a few weeks. Ulrich's design was clean and was at a further stage in development, so became the base of the future rewrite effort.

On April 5th 2006, we gave a short presentation at the Linux Wireless developers summit. LWN has a report of the summit (photo here)

On April 17th 2006, we announced initial zd1211rw usability on the mailing list.

On July 4th 2006, an early version of zd1211rw was merged into Linus' kernel, just in time for 2.6.18-rc1

On December 2nd 2006, Michael Wu ported zd1211rw to the cutting-edge mac80211 wireless stack for later inclusion in Linux 2.6.25. Also, Daniel and Michael attended the 2nd Linux Wireless Summit.

In May 2007, Atheros rebranded the ZD1211B chip but don't appear to have made other changes. The new chip name is Atheros AR5007UG (alternatively known as AR2524/AR5524). The hardware is supported by the current driver in recent kernel releases.

Subcontent

Supported Devices

zd1211rw supports devices based on the following chipsets:

  • ZyDAS ZD1211
  • ZyDAS ZD1211B
  • Atheros AR5007UG

For a complete listing of supported products, see the device list.

Status

  • Usable and stable in managed mode, provided that you are able to run a recent kernel
  • The following table indicates the feature set for the in-kernel zd1211rw driver

Feature

Status

ZyDAS chips supported

ZD1211 and ZD1211B (in one kernel module)

RF types supported (ZD1211)

AL2230, AL2230S, RF2959, AL7230B, UW2453

RF types supported (ZD1211B)

AL2230, AL2230S, AL7230B, UW2453

Support for multiple concurrent devices

yes

Connecting to open networks

working

Connecting to WEP networks

working

Connecting to WPA networks/wpa_supplicant

working

Monitor mode

working

Mesh mode

working, see o11s project site

Master mode

working

Ad-hoc mode

working

802.11a support

not yet

802.11w support

working

Largepacket + TX-burst support

not yet

Automatic rate selection/management

yes

iwconfig parameters supported

essid, mode, key, channel, ap, rate

Ability to change MAC address

yes

Power management support

? (probably not yet)

Automatic TX power calibration

not yet (fixed TX power currently)

Complying with local regulations

yes (channel masks implemented)

Architectures tested

x86, PPC32, x86-64, ARM

ChangeLog

Linux 2.6.39

  • Support for master mode

Linux 2.6.26

  • Support for open80211s meshing

Linux 2.6.25

  • Driver ported to mac80211 wireless stack
  • More device IDs and bugfixes

Linux 2.6.24

  • More device IDs and bugfixes

Linux 2.6.23

  • UW2453 RF support
  • Firmware load deferred to interface up time (as opposed to device detection time: you can now build zd1211rw into your kernel image)
  • More device IDs added

Linux 2.6.22

  • AL7230B/ZD1211B support
  • More AL2230S support
  • More device IDs added

Linux 2.6.21.5

  • AL2230S RF support

Linux 2.6.21

  • More device IDs added

Linux 2.6.20

  • Multicast/IPv6 support
  • More device IDs added
  • Advanced ERP handling
  • ifconfig now reports packet statistics
  • Bug fixes

Linux 2.6.19

  • LED support
  • Support for driverless devices
  • AL7230B RF support
  • Many more device IDs added

Linux 2.6.18

  • zd1211rw added to mainline kernel

Firmware

  • Firmware is pulled from userspace, get the files here

  • The location the firmware has to be put to varies from distribution to distribution. See dmesg output if loading firmware fails.

Requirements

  • A recent Linux kernel with the mac80211 and firmware_class modules (CONFIG_MAC80211, CONFIG_FW_LOADER)
    • There is no backwards compatibility with older kernels
  • Device firmware (see above)

Performance

  • RX performance is about half that of vendor driver, will be improved (probably better now, needs re-measure)
  • TX speed should be OK, can be optimized to remove memory allocations in critical path

Debugging

  • To enable debugging, enable the CONFIG_ZD1211_DEBUG kernel option
  • You can keep an eye on softmac's activity by running iwevent in another console while you work.

USB ID's and RF types

We have *not* copied over the list of USB ID's from the ZyDAS driver. We wish to confirm that the RF is supported for each device, and that the device actually works with our driver, before we add the USB ID.

For an explanation of RF types, see this page. We'll add support for more RFs if we see them included in devices available on the market (i.e. if you tell us!).

We currently support most of the IDs listed in the vendor and vendor-based drivers, but not all. You may have to add your own ID before using the driver – there are more detailed instructions available.

Patches

If you wish to contribute, send patches to the linux-wireless mailing list with Daniel and Ulrich on CC (no subscription required). Note there are some bounties available for patches!

Please sign off on your patches, because your patch will probably end up in the kernel source.

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