********************** 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 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 http://at76c503a.berlios.de/devices.html 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. 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. UPDATE: if you're using linux-wlan-ng 0.2.1-pre6 or newer and kernel < 2.4.22-pre, the 'uhci' driver will NOT work without a kernel patch! See: http://lists.linux-wlan.com/pipermail/linux-wlan-devel/2003-May/002369.html 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 0.1.15-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: How do I know what firmware my card has? After the driver is loaded and brought into ifstate=enable, you will see the following lines in the kernel log: (eg dmesg |grep ident) ident: pri f/w: id=0x15 0.3.0 ident: sta f/w: id=0x1f 1.7.1 In this case, the card has primary firmware 0.3.0 and secondary firmware 1.7.1. Or, if you are using 0.2.1-pre17 or newer: 'cat /proc/net/p80211/wlan0/nsd' with the card running. Q: How can I update my firmware under Linux? Use the 'prism2dl' utility. While it does its utmost to ensure you don't fry your card, use it at your own risk. Even the Intersil-supplied tools fail occasionally. Q: Where can I download updated firmware for my Prism2/2.5/3-based card? As of linux-wlan-ng 0.2.1-pre21, the ram download firmware for all supported card types is bundled with the driver. These images cannot be flashed. A general FAQ on firmware updating is here: http://linux.junsun.net/intersil-prism It includes links to some sites with firmware images. We strongly recommend against flashing a new image, instead one should use the ram-download images that are loaded when the driver starts, much like the Windows drivers do. See the instructions below for getting this to work. Q: What's this about "ram downloading"? This means the driver loads up a firmware images directly into card RAM, instead of using the firmware stored in the card's flash ROM. This lets us ensure we are using the lastest available code without risking ruining the hardware due to a bad flashing. linux-wlan-ng will automatically perform a RAM download if you have the necessary firmware images. Q: Okay, I have new ram download firmware images, where do I put them? copy the *hex files into linux-wlan-ng-XXXX/src/prism2/ then build and install the driver per usual. 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/ 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 Q: I'm using RedHat 8.x, and I get this error when trying to ifup wlan0: Error for wireless request "Set Encode" (8B2A) : SET failed on device wlan0 ; Function not implemented. Error for wireless request "Set ESSID" (8B1A) : SET failed on device wlan0 ; Function not implemented. You can safely ignore this; it is there because linux-wlan-ng does not currently use the wireless extension commands for configuration. Q: When the prism2_cs module loads, I see the message "RequestIRQ: Resource in use" and the load fails! What's going on? Is your card a 16-bit PCMCIA card? If it is, you may need to recompile your kernel with ISA bus support enabled (CONFIG_ISA=y). The PCMCIA core uses ISA bus support to help determine what IRQs are available for the card. Without it, the PCMCIA core may not be able to select an IRQ. Q: After installing linux-wlan-ng on my RedHat 9 system, pcmcia no longer works! This is due to a bug in the RedHat 9 pcmcia startup scripts. On or about line 105 in /etc/init.d/pcmcia, remove all of the '.o' suffixes on the modprobe command lines. It should read something like this: if [ -d $PC ] ; then echo -n " modules" /sbin/modprobe pcmcia_core $CORE_OPTS /sbin/modprobe $PCIC $PCIC_OPTS /sbin/modprobe ds elif [ -d $KD ] ; then /sbin/modprobe pcmcia_core /sbin/modprobe $PCIC /sbin/modprobe ds else Q: When starting the device, I get the following error: '/sbin/prism2dl not found' This is just a warning; the intialization sequence will continue on just fine. linux-wlan-ng supports the ram-download of firmware images into the card. Linux-wlan-ng 0.2.1-pre17 or newer includes the downloader, rendering this moot. Q: I found a copy of prism2dl on the net, installed it and now I get the following error on startup: 'prism2dl: Failed to read prism2_XX.hex, exiting.' This means it didn't find the necessary firmware file to perform a RAM download. As distributed by Intersil (and most vendors) the filenames use the following convention: rf010409.hex 'rf' is image name, while '010409' refers to v1.4.9. copy all the images you have to the src/prism2 directory, and run 'make install'. the images will be renamed and copied to the appropriate place and everything will be happy. Note that the filename needs to be lowercase. Q: I have a D-Link DWL-650P or a DWL-520E, why doesn't it work? These cards are the first generally-available ones that use a short serial flash, or SSF. In layspeek, it means that there is no onboard firmware, and thus need the firmware loaded into the card on startup. linux-wlan-ng 0.2.1-pre17 supports SSF hardware, and -pre21 includes firmware files with it.