linux-wlan-ng/FAQ

********************** Linux-wlan-ng FAQ **************************
For additions, corrections, and clarifications, send mail to
solomon@linux-wlan.com with FAQ in the subject.
*******************************************************************

Q: What devices does the linux-wlan-ng driver support?

	Currently, the linux-wlan-ng driver supports the Intersil
	Prism2/2.5/3 chipsets.  These chipsets are used in a wide
	variety of PCMCIA, PCI, and USB products.  If it has a Prism
	chip in it, linux-wlan-ng should support it.

Q: Will linux-wlan-ng support some feature or funkiness in
   the <pick one> Linux distribution?
 
	Our development target always consists of stock kernels from
	kernel.org and stock pcmcia_cs.  If a given distribution
	chooses to do something funky, we rely on users of that
	distribution to contribute patches to deal with their
	funkiness.

	The quickest way to get some action on this kind of item is to
	communicate with any users of the same distribution that you
	can find on the linux-wlan-[devel|user] lists about working up
	a patch.  If it's reasonably sane and doesn't break things for
	our development environment or for other distributions, we'll
	be more than happy to roll that patch into the next release.  

Q: What does "resultcode=implementation_failure" mean?

	Complicated Answer: 
	Each command that can be issued with wlanctl-ng returns a status
	called "resultcode".  Resultcode is something that we picked up
	from the 802.11 MLME definition.  In the standard, resultcode
	is an enumeration with a fixed set of values.  To be able to
	report failures that a driver detects that are outside the
	context of the 802.11 standard set of resultcode values, we 
	invented the "implementation_failure" value.

	Simple Answer:
	Go look in your kernel log for more detailed error information.

Q: I'm trying to use the HostAP/orinoco/aironet/wvlan driver and it
   won't work!

	That has nothing to do with the linux-wlan-ng driver.  Go ask
	those responsible for those drivers.

Q: Can I get Debian packages of linux-wlan-ng?
 
A: Packages of linux-wlan-ng are available in the Debian unstable
   and testing trees now, and will eventually be shipped with a stable
   Debian release. The Debian packages include support for configuring
   linux-wlan-ng interfaces via /etc/network/interfaces, amoung other
   things. Complete details about the Debian-specific parts of these
   packages, including instructions for building a linux-wlan-ng modules
   package for your kernel can be found in the file

   /usr/share/doc/linux-wlang-ng/README.Debian.gz

Q: Where do I find some RPMS for linux-wlan-ng? The ones on
    the ftp are dreadfully out of date!

	http://prism2.unixguru.raleigh.nc.us/

	(Maintained by Tim Miller)

Q: I installed the RPMs/compiled the driver and installed it and it
   won't work when I try to run 'ifup wlan0' or whatnot.

	First, ensure you're running the most up-to-date version of
	the driver.  Many problems have been fixed in newer releases.

	802.11 wireless networks are much more complex than wired
	ethernet networks.  They require much more configuration than
        an ip address.   If you are using pcmcia, edit the file 
        /etc/pcmcia/wlan-ng.opts to set the network parameters.  For
        PCI, PLX, or USB adapters, you need to edit /etc/wlan.conf.
	
	You also need to make sure you have the correct settings in
	/etc/modules.conf (alias wlan0 prism2_usb). 

	Might we suggest you read the README file?

Q: When I try to load the driver, I get a whole bunch of errors about
   unresolved symbols.

	The running kernel does not match the kernel the driver was
	compiled for.  If you downloaded a RPM, make sure you
        downloaded the correct version for your kernel.  This should not
        happen if you compiled the driver from source -- if it does, the
        kernel configuration you compiled against does not match the
        running kernel.  Probably a screwed-up distro kernel.

Q: I have a DWL-520 and it won't work!

	The DWL-520 claims to require a PCI 2.2 compliant motherboard.
        Only fairly new machines support this.  Yes, the box lies.  :)
        Check the documentation for your system and/or motherboard to see if 
	it is PCI 2.2 compliant.  

	NOTE:  We have some reports of the DWL-520 working on PCI 2.1
	motherboards; your mileage may vary.  See the following URL:

		http://www.personaltelco.net/index.cgi/DlinkDwl520

        NOTE:  The Linksys WMP11 v2.7 is NOT prism-based, and
	thus not supported by this driver.  The Actiontec PCI board is
	still known to be prism based; you may want to try that instead.

Q: All I see is "Tx attempt prior to association, frame dropped"

	You are not associated with an access point.  Double-check the
        settings in /etc/wlan.conf (USB, PCI, PLX) or /etc/pcmcia/wlan-ng.opts
        (for PCMCIA users).    If all of these settings are correct (you
        did check with your admin, right?) make sure the access point
        doesn't have a MAC filter installed or has different WEP settings.

	If all of this is verified correct, and are using a PCMCIA
	card, try setting the "irq_mode=0" option.  See the
	documentaiton in the pcmcia-cs sources.

Q: I installed the modules, performed a 'wlanctl-ng wlan0 lnxreq_autojoin'
   command, and it still won't work!

	You did read the README, didn't you?  You need to perform a 
	"wlanctl-ng wlan0 lnxreq_ifstate ifstate=enable" in order to
        torn on the radio.  The pcmcia scripts and the /etc/init.d/wlan
        script do this for you.

Q: I have a XXX USB 802.11b device, will it work with this driver?

	Most 802.11b USB devices use the ATMEL AT76C503A chipset, which
        is not supported by the linux-wlan-ng project.  However, there
	are some prism2.5-based USB adapters, most notably the Linksys
	WUSB v2.5.  The other versions (1.0, 2.6, 3.0) are based on
        ATMEL chipsets.  Another supported USB device is the Actiontec
	802UI3.

Q: The wlan-ng driver says my ATMEL AT76C503A device is unsupported!

 
	Atmel has placed the source code of the Linux driver for the 
	AT76C503A (and 501 or 502 - the PCMCIA variant) under the GPL 
	in July 2002. The project can be found under

	http://www.sourceforge.net/projects/atmelwlandriver

	and it is in a rather usable state.  The mailing list

	http://iprserv.jura.uni-leipzig.de/mailman/listinfo/atmel-wlan-usb

	still has many useful postings.

Q: My prism2.5-based USB adapter won't work!

	An excellent guide can be found at:

	http://www.fuw.edu.pl/~pliszka/hints/prism2.html
	
Q: My prism2.5-based USB adapter won't come up if it's plugged in at boot! 

	Thanks to buggy firmware, it is often necessary to perform a
        device reset on initialization.  You can perform this by adding
        "options prism2_usb prism2_doreset=1" in your /etc/modules.conf

	Intersil has released Primary firmware 1.1.2, which seems to
	have resolved this problem, at least on our test machines.
	Contact your vendor for a firmware update.

	To check the firmware version, run: "dmesg |grep ident"

Q: My PC crashes when the USB device is plugged in!

	This is a result of the port reset necessitated by buggy firmware.

	You are probably using the 'usb-uhci' driver with an intel
        chipset.  Unfortunately, the crashes happen deep within the USB
        core, so there's nothing the linux-wlan-ng driver can do.

	In the mean time, try using the 'uhci' host controller driver
        instead ("alias usb-controller uhci" in /etc/modules.conf), or
        plug the USB device into a hub.

	Linux kernel 2.4.19 is known to improve the situation somewhat,
	but the right way to fix it is to turn off the port reset
	(options prism2_usb prism2_doreset=0).  The current firmware
	from Intersil alleviates the need to perform the reset.

Q: My PC crashes when the USB device is unplugged!

	0.1.16-pre3 included some fixes that should eliminate the race
	condition that caused the oops-on-unload.

Q: What's with these "Called from within soft interrupt context" messages?

	This is the result of a workaround to avoid a kernel oops in
	the USB driver code.  You can ignore them.  

	As of 0.1.15-pre5, a different workaround is in place.

Q: Why doesn't promiscuous mode or monitor mode work under USB?

	Promiscuous mode works just fine, as of 0.1.15-pre5.

	Monitor mode also works, as of 0.1.14-pre6.

	Both modes are likely to be quite unreliable, especially under
	higher loads thanks to fundamental bandwidth limitations of the
	USB interface.  

Q: How come I can't transmit when in monitor mode?

	You can't.  It's a fundamental "feature" of the hardware.

Q: How come the /proc/net/wireless info isn't updated when in monitor mode?

	The definition of "signal quality" refers to the quality of the
	link to the associated access point.  When you're in monitor
	mode, you're not associated, so this information is by defintion 
	irrelevant.

	And regardless, the hardware doesn't update the registers we poll to
	obtain this information while in monitor mode.

Q: What do the various monitor mode options do?

	enable=[true/false]           Turn it on and off.  required.
	channel=[1-14]                Sniff channel.  required.
	prismheader=[true/false]      Optionally preppend a special
                                      radio header on the packet.
				      Defaults to off.
	keepwepflags=[true/false]     If you had WEP configured correctly
				      the card will perform WEP decoding.
				      Defaults to off.
	stripfcs=[true/false]         When true, the 802.11 FCS is not
				      stripped from incoming packets.
				      Defaults off.
	truncate=[number]             Truncates the captured frame.  

Q: How come iwconfig/iwspy/[random other wireless tool] doesn't work?
	
	linux-wlan-ng only supports a subset of the wireless
	extensions; generally read-only things.  However, you won't
	need any of those tools as wlan-ng comes with its own set of
	tools that closely mirror the 802.11 spec.  Have a look
	through the documentation and supplied scripts.

	That said, if more complete (ie read/write) wireless extension
	support is really important to you, you're more than welcome to
	implement it and submit a patch.  

	As of 0.1.16-pre1, the wireless extension plumbing has been
	re-written, and further support is much easier now.  And many
	more bits are hooked up now than before.

Q: How do I know exactly what prism variant is on my card?

	When you load the driver, you see a line which reads like:

		ident: nic h/w id=0x8008 1.0.0
                                         
	1.0.0 is the hardware revision.  Below is a (partial) list of IDs.

		0x8003, 0x8008 :  Prism2 PCMCIA

		0x800b, 0x800c :  Prism2.5 PCMCIA
		0x8012, 0x8013 :  Prism2.5 PCI
		0x801a, 0x801b :  Prism3 PCMCIA
		0x8021, 0x8022 :  Prism3 PCI
		
		0x800f, 0x8010 :  Prism2.5 USB  (3863)
		0x801e, 0x801f :  Prism2.5 USB  (3861B)
		0x8025, 0x8026 :  Prism3 USB
		

Q: Where can I download updated firmware for my Prism2/2.5/3-based card?

	Ask your vendor.  Due to legal reasons, we cannot
	provide updated frmware with the driver code.

Q: How can I update my firmware under Linux?

	Use the 'prism2dl' utility.  Note that it has been removed from
	newer revisions of the driver sources due to liability reasons --
        too many people fried their cards and blamed AVS for it.

Q: Can I use my 802.11b card as an AP under Linux?

	Yes, and in the true free software fashion, there are several
	ways:

	a) linux-wlan-ng supports AP operation by using special tertiary
	   firmware on prism devices.  This firmware is not generally
	   available, however.   Contact Intersil for licensing terms.

	b) The Prism2 HostAP driver uses the special HostAP mode of the
           prism chipsets.            http://people.ssh.com/jkm/Prism2/

	c) The OpenAP project, which involves flashing Linux on access
           points.                    http://opensource.instant802.com/

Q: After a few minutes of use, my card stops responding!  I'm using WEP.

	There seems to be card lockup problems with newer cards (new
	DWL-650 cards, linksys WPC11v3) when WEP is turned on.  Since
	WEP is done in hardware, there is nothing the driver can do to
	resolve this.  We suggest you pester your vendor for a firmware
	update.

	Prism2.5 boards are also known to lock up under heavy use; this
	is due to bugs in the WEP engine.  Even if you perform a card
	reset, the WEP engine remains stuck.  

	As an alternative, you can try out the host-based WEP present in
	0.1.15-pre1 and newer.  It is still considered experimental,
	but the person typing this uses it on a daily basis.

	Intersil claims to have fixed this in firmware 1.4.0:

	"Fixed a hang condidion seen on certian hardware designs when
          using firmware WEP"

	Note there are other bugs in the firmware; as recently as 1.4.5
	Intersil included a fix that would "Correct an error that could 
	cause the driver to no longer be able to communicate with the
	firmware"

	Contact your vendor and ask them to release updated firmware.

Q: When using host-based WEP I get these strange intermittent connection
   lockups.

	This should be fixed in 0.1.15-pre3.  If you are sill having
	problems, send a detailed message to the linux-wlan-devel
	mailing list.

Q: When using the wlan-ng driver on a multiprocessor machine, I get
   packet corruption or random crashes/lockups.

	0.1.15-pre2 is the culmination of a major restructuring of
	internal driver locking..  Please give it (or newer) a shot
	if you're using a SMP system; we expect it to be much improved
	even on uniprocessor systems as we lock out system interrupts for 
	far less time now.

	0.1.16-pre3 included a fix for a subtle SMP deadlock that was
	missed in 0.1.15-pre2 and earlier.

	0.1.16-pre4 included workarounds for PrismPCI hardware errata
	that would also manfest themselves as SMP problems, but could
	also affect uniprocessor machines in rare circumstanes.

Q: I have a PCI adapter, and upon resuming from a suspend, the device is not
   responsive.  

	Much like you need to run some commands to bring the card to life 
	when the PC is first booted, you also need to perform similar 
	steps when the card comes out of suspend.   Run '/etc/init.d/wlan start'
	and all should be well.

	You'll need to be running 0.1.15-pre3 or newer for this to work
        properly.

	The prism2.5/3 chipsets do not support PCI power management, so
	this is the best we can realistically do.

Q: I have a Linksys WMP11, and under moderate to heavy traffic, I get
   errors like "unknown port number" and "invalid frame type"

	Make sure you're using the latest firmware avaliable from
	Linksys's web site.  According to the firmware release notes:
	
	 "Changes were made to prevent erroneous data from being 
          transferred over the PCI bus"

	Note that this problem has also beeen confirmed on the D-Link
	DWL-520.  You will need firmware 1.3.5 or newer to resolve this.

Q:  I have a D-Link DWL-650/650+/520+ card, why doesn't it work with
    this driver?

	The DWL-650 comes in three flavors; older ones have grey
	antennae, with no revision number on the back.  
	Second-generation  has a black antenna and the back reads 
	"H/W J3 F/W 1.x.x". Both of these will work.  The third-
	generation, with a grey antenna, has "H/W A1, F/W x.x", and
	will NOT work;  It has the same hardware as the "plus" series
	of cards.

	The "plus" series of cards from D-Link use the Texas Instruments 
	ACX100/TNETW1100 chipset.  TI has not been forthcoming with 
	programming information.  Politely ask TI and D-Link for Linux
	drivers and/or docs.

	We've been told that TI will be releasing binary-only Linux
	drivers sometime in December.  In the mean time, return the
	card and buy one that works with Linux.
	
Q: I have a Linksys WMP11 v2.7 card; why doesn't it work with this driver?

	Linksys, in their grand tradition, likes to introduce completely
	new cards but re-use the model number.  The WMP11 v2.7 utilizes the
	Broadcomm chipset, and is not supported by linux-wlan-ng.  Politely
	ask Linksys and/or Broadcomm for Linux drivers and/or docs.

Q: What other resources are there for Wireless LANs under Linux?

	http://www.fuw.edu.pl/~pliszka/hints/wireless.html

	http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Linux.Wireless.drivers.html