********************** 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
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.