[mdlug] Attempts at manually restarting wireless kernal module

[Peter Bart]

On Sun, 2009-12-13 at 00:19 -0500, Drew wrote:
> Per my discussion with a couple of members at today's mdlug, I'm 
> recapping my efforts at
> solving an issue with the wireless card in my desktop computer.
> 
> What I need to do:
> 
>      Remove the module which runs the acx100 wireless card, then put 
> it back in, without
> rebooting the entire system.
> 
> Why:
> 
>      It's the only reliable means I've found so far to restore a 
> wireless connection after something
> (interference from aircraft radar probably) screws up the connection.
> 
> Telling when the connection gets screwed up:
> 
>      I've found that the loss of connection correlates strongly with 
> the Signal Strength number in
> /proc/net/wireless for wlan0. A working connection will have this 
> number (a) almost always
> ending in a decimal point or period ("."), and (b) varying in value 
> almost every second. When a
> connection goes bad, this number becomes *constant* - and is never 
> zero!. Also, the ending
> decimal point/period disappears. A script that I had running in 
> Fedora 4 watched for this condition
> as a signal to restart the module.
> 
> Previous handling:
> 
>      As indicated, I had the problem solved "in software" under 
> Fedora 4 with a script that watches
> for the connection to go bad, then runs other scripts that came with 
> the driver that I had previously
> downloaded, compiled, and installed separately (Fedora 4 itself did 
> not come with an acx100 driver),
> which rmmod'ed then insmod'ed the module. This not only restored the 
> connection (at least until
> it would get jammed again) but allowed downloading already in 
> progress to continue and eventually
> finish.
> 
> Current situation:
> 
>      I'm now running Suse 11 which comes with an acx driver. 
> Unfortunately, even though it starts up
> properly during boot, removing and reinserting the module fails when 
> attempted from the command line.
> dmesg indicates that it is failing to find the card firmware files 
> (in /lib/firmware). The previous driver
> accepted a firmware_dir= parameter, but this version does not. Nor 
> have I been able to figure out just
> how it's managing to find these files during boot.
> 
> I've tried the following:
> 
>      insmod and rmmod, and modprobe. Fails to find firmware.
> 
>      insmod/rmmod/modprobe with firmware_dir=/lib/firmware. Does not 
> recognize parameter; "invalid symbol"
> 
>      Recompiling the previous driver for Suse 11. Fails due to a 
> missing config.h somewhere; apparently Suse 11
> has bad kernel sources.
> 
>      Creating a new Fedora 4 partition. *Works!* However, there are 
> other problems with this too numerous
> to deal with, including Flash Player refusing to install due to 
> missing glibc. (Fedora 4 glibc is probably too
> out of date for current Flash Player.)
> 
> 
>      Per suggestion at mdlug:
> 
>      rcnetwork start, restart, and try-restart. Runs without error, 
> but does not restore the signal strength
> number to a "good" condition (Remains flatlined).
> 
>      hald, udevd, and udevadm trigger. Does not restore wlan0, nor do 
> any of them correct the flatline
> condition if I leave the module in.
> 
> 
> What I am seeking: Any of the following:
> 
>      What exactly to enter as a parameter, or otherwise how to get 
> the kernel to know where to find
> those firmware files.
> 
>      How exactly this is being done during boot (when the files *do* 
> successfully get found).
> 
>      Generally, how to find out, from the .o or .ko file, what 
> parameters a kernel module takes.
> 
>      Where or how to get a log of the commands, with their 
> parameters, that get executed during
> boot - especially those that start kernel modules - as opposed to 
> just the output which dmesg
> gives. To wit, an input equivalent of dmesg.
> 
>      A way to "restart" a kernel module without removing it. 
> Something like a modprobe --restart.
> 
>      Any other way to actually shut down and restart the card itself 
> (not just the "network"). That
> is, restart it at the hardware level.
> 

	I would be very interested in what you find. I may have the same
trouble,openSUSE 11.1/Gnome and my wireless just stops working after a
while. I use notebooks; with two different wireless cards; so there are
suspend/resume cycles involved. Usually a <service network stop>
<service network start> is enough to get things going. Sometimes I have
to <service network stop> <modprobe -r iwl4965> <modprobe iwl4965>
<service network start> My understanding is that modprobe -r removes the
wireless driver, and modprobe inserts it. I believe I found it on
openSUSE's forum as a temporary work around. 

-- 
Best Regards,

Peter The Plumber