Re: Debugging iwlagn intermittent connectivity issue

[Dan Williams <dcbw redhat com>]

On Tue, 2009-06-09 at 11:59 -0700, Paul Jones wrote: 
> On Tue, Jun 9, 2009 at 8:53 AM, Dan Williams<dcbw redhat com> wrote:
> > On Mon, 2009-06-08 at 15:20 -0700, Paul Jones wrote:
> >> Hi,
> >>    I was hoping to get some help with a intermittent connectivity
> >> issue using Ubuntu Intrepid (8.10). My wireless connection (iwlagn)
> >> seems to fail intermittently for 15-30s at a time as frequently as
> >> every couple of minutes. NetworkManager doesn't report that the
> >> connection has failed and there doesn't seem to be anything of note in
> >> syslog or wpa_supplicant.log.
> >
> > What kernel version?  Kernels earlier than 2.6.30 have bugs relating to
> > scanning that could well be causing your problem.
> $uname -a
> Linux Athena 2.6.27-11-generic #1 SMP Wed Apr 1 20:53:41 UTC 2009
> x86_64 GNU/Linux

I'd suspect that the lack of scanning patches in your kernel is the
problem.

commit a9a6ffffd05f97e6acbdeafc595e269855829751
Author: Kalle Valo <kalle valo nokia com>
Date:   Wed Mar 18 14:06:44 2009 +0200

You'll also want to try turning on software scanning instead of the
hardware scanning, which can help in some cases with older kernels (ie,
before 2.6.30).  That can be accomplished by passing the driver
"disable_hw_scan=1" when modprobing it, usually via file dropped
into /etc/modprobe.d/ that contains:

options iwlagn disable_hw_scan=1

Dan

> >Are you loading
> > iwlagn with any module options?
> Just the default options that Ubuntu provides.
> >systool -m iwlagn -av
> Module = "iwlagn"
> 
>   Attributes:
>     initstate           = "live"
>     refcnt              = "0"
>     srcversion          = "5226C1C38C52E6FF73CF4C8"
>     version             = "1.3.27ks"
> 
>   Parameters:
>     11n_disable         = "0"
>     11n_disable50       = "0"
>     amsdu_size_8K       = "1"
>     amsdu_size_8K50     = "1"
>     antenna             = "0"
>     debug               = "0"
>     debug50             = "0"
>     disable50           = "0"
>     disable_hw_scan     = "0"
>     disable             = "0"
>     fw_restart4965      = "1"
>     fw_restart50        = "1"
>     qos_enable          = "1"
>     qos_enable50        = "1"
>     queues_num          = "16"
>     queues_num50        = "20"
>     swcrypto            = "0"
>     swcrypto50          = "N"
> 
>   Sections:
>     .bss                = "0xffffffffa03b1c00"
>     .data               = "0xffffffffa03aeaa0"
>     .devexit.text       = "0xffffffffa03a6044"
>     .exit.text          = "0xffffffffa03a6028"
>     .gnu.linkonce.this_module= "0xffffffffa03afa00"
>     .init.text          = "0xffffffffa006e000"
>     .note.gnu.build-id  = "0xffffffffa03a61f8"
>     .parainstructions   = "0xffffffffa03a8628"
>     .rodata             = "0xffffffffa03a6220"
>     .rodata.str1.1      = "0xffffffffa03a815c"
>     .rodata.str1.8      = "0xffffffffa03a67a8"
>     .smp_locks          = "0xffffffffa03a84b0"
>     .strtab             = "0xffffffffa03abf00"
>     .symtab             = "0xffffffffa03a8918"
>     .text               = "0xffffffffa0396000"
>     __bug_table         = "0xffffffffa03a83d5"
>     __param             = "0xffffffffa03a8648"
> 
> 
> 
> >
> > Dan
> >
> >>    I have no idea where this bug could be located and I would like
> >> some help with debugging. I have experienced the bug using three
> >> difference AP. I haven't eliminated a hardware issue however, as I've
> >> only run this laptop using Intrepid. But hardware seems unlikely as
> >> the problem is alleviated by rebooting. I have experienced the bug
> >> with every Intrepid kernel that has been released thus far. The bug
> >> seems to occur mainly when the wireless network is under load. For
> >> instance, when I'm streaming videos off of Hulu.
> >>
> >>    I have posted a bug report here
> >> (https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/384924).
> >> It should contain much of the relevant information.
> >>
> >>    I appreciate any help your experience can bring. Thanks for your time
> >>
> >> Paul
> >> _______________________________________________
> >> NetworkManager-list mailing list
> >> NetworkManager-list gnome org
> >> http://mail.gnome.org/mailman/listinfo/networkmanager-list
> >
> >