Laptop caution: FC7, you can either have wireless networking or suspend. Maybe not both, for a while

[Paul Johnson]

Hello, laptop users:

Maybe I mean to ask: how to we use the driver iwl3945?  OR maybe I
mean to say iwl3945 doesn't work--if you are happy with FC6, don't
upgrade to FC7 yet!

I upgraded a Dell Latitude D820 laptop from FC6 to FC7.  After
rebuilding the ipw3945 kernel module, I found that my wireless
networking was still working, mostly.  There is trouble joining some
networks and NetworkManager just doesn't work lots of the time in
joining hotspots, but that was always true.

But then I found my laptop cannot suspend/resume.  One problem was the
newer Nvidia driver causes a kernel oops when X closes, but that's
easy to fix by going back to the previous Nvidia driver.  The more
serious problem, it appears, is that the kernel's new suspend system,
pm-suspend, is not compatible with the ipw3945 drivers and the
regulator daemon ipw3945d.

When the suspend problem was reported on the fedora email list, people
 (in a somewhat cavalier way, I must say) pointed users at the
pm-suspend quirk page,

http://people.freedesktop.org/~hughsient/quirk/quirk-suspend-index.html

which states that suspend will never work as long as people keep
trying to use the Intel ipw3945 driver and ipw3945d.  It says we ought
to use the new iwl3945 wireless driver, which is in the kernel that
comes with FC7.

I can't find any user documentation on how to work with the iwl3945.
The iwl3945 driver does not show up in system-config-network.  I can
make some guesses, turning NetworkManager on and off,
system-config-network, and manually editing files in
/etc/sysconfig/network-scripts.  I can use iwl3945 to join some
wireless networks.  But performance is really spotty--association
fails, or quits most often.

I have tested iwl3945 a lot, and there are a lot of wrinkles that I
don't understand.  It appears to me that /sbin/iwlist scan never works
when the iwl3945 driver is being used.

Anyway, I suppose this is just a warning to people using FC6 on
laptops with the Intel wireless.  I'd say that, if your system
currently works, DO NOT upgrade if you currently use suspend.  I think
there is a time in the future when iwl3945 will work dependably,
because the Intel team has always done a good job in my experience
(developing the ipw2200 and ipw3945 drivers).  But iwl3945 is
currently a mystery.  And, when it does work, then there is a separate
problem of learning to make pm-suspend work together with it.

In case you are using the iwl3945 with success, maybe you can tell us
how you do it.  OR at least you can clear up some stuff for me.  When
iwl3945 is loaded, WHY do I have a device "wmaster0" and why does a
non-attached eth1 look so weird?

# /sbin/iwconfig
lo        no wireless extensions.

eth0      no wireless extensions.

wmaster0  no wireless extensions.

eth1      IEEE 802.11a  ESSID:""
          Mode:Managed  Channel:0  Access Point: Not-Associated
          Retry min limit:7   RTS thr:off   Fragment thr=2346 B
          Encryption key:off
          Link Quality:0  Signal level:0  Noise level:0
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0


And why does iwlist scan return nothing, whereas I do see access
points with ipw3945.  In what sense does it mean the Network is down?
This it what it looks like after I boot up with NetworkManager
disabled.  The iwl3945 module is loaded, but no scan.

# /sbin/iwlist scan
lo        Interface doesn't support scanning.

eth0      Interface doesn't support scanning.

wmaster0  Interface doesn't support scanning.

eth1      Interface doesn't support scanning : Network is down


And after I try to join a network, I see this.

# /sbin/iwlist scan
lo        Interface doesn't support scanning.

eth0      Interface doesn't support scanning.

wmaster0  Interface doesn't support scanning.

eth1      No scan results


pj

-- 
Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas