faq.isa

Linux Wireless LAN Project 的目标是开发一个完整的

Here are some FAQ and their possible solutions

Thanks to the following people for their real-life contributions:
        Adrian Perez Jorge <[e-mail]>
        Jeremy Dueck <[e-mail]>
	Chris Audley <[e-mail]>
        Mark S. Mathews <[e-mail]>

- wlantcl: card detect ioctl failed

    You may not have given a correct isapnp.conf file. Make sure it
    matches your card (check with pnpdump) or the IRQ and/or IOBASE
    are wrong.
    The ISA cards should work fine on 
	IRQs     9, 10, 11 and 12, 
    	IOBASEs  x240, 0x280, 0x2c0, 0x300, 0x340, 0x380, 0x3c0 
    (i.e. steps of 0x40). Simple replace those values in the /etc/isapnp.conf
    file.
    Obviously you need to make sure that the IRQ and IOBASE you want to use
    are not in use by somebody else. One of the symptoms might be that you
    don't see any interrupts on the card, so commands like "wlanctl" may
    never finish.

    (According to the Am79C930 data book pp 64:
    "Any of the following channels within an ISA Plug and Play system may be
     utilized by the Am79C930 device:

     IRQ 4, 5, 9, 10, 11, or 12. "
     but isapnptools is know to claim that a more restrictor set
     (9,10,11,12) are allowed. So, be careful with 4 and 5.

- cannot find module am930_isa

    sometimes (older kernels 2.0.x?) it happens that despite that you
    have installed the modules, and they are in the right place
    (/lib/modules/`uname -r`/pcmcia), you need to insmod them using
    an absolute path, e.g.:


insmod /lib/modules/`uname -r`/pcmcia/am930_isa.o am930_irq=9 am930_iobase=0x240

    instead of the usual shorter

insmod am930_isa am930_irq=9 am930_iobase=0x240


- My network performance has gone bad once I added a second WLAN on a 
  different channel.

    Make sure your second channel is separated by at least 5 channels. So,
    using channels 1, 6 and 11 is safe if you need 3 different networks.
    The reasons is that neighboring channels have too much interference.

- My network performance is not great.

  Before installing an outdoor antenna I had weak signals and a low bitrate.
  Then I decreased MTU to a lower value so I could do some transfer without
  locking:
        ifconfig eth0 mtu 512
  or so. The default for high speed ethernet is 1500.


- Sometimes my network interface seems to hang. How can I solve this?

    You can safely re-execute your rc.wlan file, it will bring your
    relevant ethN (eth0, eth1, ...) down, and up again. Do not remove
    the am930_isa module from memory though, they are not built for 
    that. Only in odd cases would you need to reboot your machine
    to fix this problem.

- In certain locations I can get very bad ping times, and the network
  can hang.

    Also try  to see if rotating the equipment helps. Sometimes your
    signal is polarized and in my case I could see differences in 90
    degree rotations in the marginal cases.


- How can i get two ISA card in the same machine to work?

    insmod has the -o and -x flags for make different names and not
    have it export all of its external symbols. So, you can try
    something like

    insmod am930_isa am930_irq=9  am930_iobase=0x240 -x -o am930_isa1
    insmod am930_isa am930_irq=12 am930_iobase=0x300 -x -o am930_isa2

- I still have intermittent problems with my ISA card and i have no idea
  what is going on... 
  The driver activates and the rx/tx lights light up as normal but
  you can't connect to any. It almost seemed like the receive sensitivity 
  was much lower than usual.

    Make sure your power supply is enough. I've heard of 150W type machines
    that were clearly not giving enough power to the ISA card. Make  sure you
    have a 250W power supply

- Card is recognized, the 'wlanctl getmib' command works ok, but scanning 
  the net (netlist) never finds anything. 
  Upon further hacking it seems like the driver isn't receiving any interrupts
  (hence the reason the scan stalls).

     This problem had absolutely nothing to do with the driver - 
     despite having gone through the whole pnpdump/isapnp routine,
     the card/BIOS wasn't being setup on the right IRQ - put the whole
     lot into a different machine, hardwired the IRQ and it all works 
     beautifully now.

- Those blinking lights went steady and my link seems dead.
  What does that mean? My driver also seems to hang.

  It could be your driver has gone sour. Under normal circumstances on
  my card the 3 LEDS (if your card is different, ignore this section) are:
  Red for power, which should be steady if you have power, green for
  Transmit, Orange for Receive.  When my ISA card comes up, orange (Rx)
  blinks rapidly at a few Hz, and green (Tx) is steady.
  Completely steady orange and green (or off) lights probably mean trouble. 
  Your driver may have gone sour. Try and re-run rc.wlan (but don't reload
  the module, or else do a reboot, my rc.wlan should do that fine).

  However, note that the LEDs are something implemented by the manufacturer,
  and not specified by IEEE 802.11, and hence you should not weigh these
  comments to high.