I've had an intermittent system hard freeze problem for 2 years. Today I was finally able ro reproduce it.
I have a Dell Latitude E4300 laptop with Intel WiFi Link 5100 wireless adaptor. Whenever I switch to 11Mbps speed:
$ sudo iwconfig wlan0 rate 11M
causes a total system freeze from which I cannot recover even using the Magic SysRq+REISUB key sequence. This is especially a problem because I think (but have no evidence) automatic switching to this speed causes system freeze as well (which results in intermittent problems).
It is noteworthy that I can reproduce the same crash on a Lenovo ThinkPad X230 with an Intel Ultimate-N 6300 wireless adaptor. Switching to 11Mbps results in a total system freeze on this laptop as well. I think the only related common module between these laptops is iwlwifi driver.
I don't know whether this depends on my connection too or not, but here is my connection information just in case:
$ sudo iwconfig
lo no wireless extensions.
wlan0 IEEE 802.11abgn ESSID:"XXXXXXXXXXX"
Mode:Managed Frequency:2.437 GHz Access Point: XX:XX:XX:XX:XX:XX
Bit Rate=21.7 Mb/s Tx-Power=15 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off
Link Quality=51/70 Signal level=-59 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:597 Invalid misc:2117 Missed beacon:0
eth0 no wireless extensions.
In case there is any more information I can provide to help triangulate the problem further, let me know.
---
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu12
Architecture: amd64
ArecordDevices:
**** List of CAPTURE Hardware Devices ****
card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: hossein 1933 F.... pulseaudio
Card0.Amixer.info:
Card hw:0 'Intel'/'HDA Intel at 0xf6adc000 irq 47'
Mixer name : 'Intel Cantiga HDMI'
Components : 'HDA:111d76b2,1028024d,00100302 HDA:80862802,80860101,00100000'
Controls : 26
Simple ctrls : 12
DistroRelease: Ubuntu 12.04
HibernationDevice: RESUME=UUID=279e54ac-43a3-4a55-a62e-7bb43680e038
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
MachineType: Dell Inc. Latitude E4300
Package: linux (not installed)
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-29-generic root=UUID=d2a40456-31e0-4564-b9a1-633089047264 ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 3.2.0-29.46-generic 3.2.24
RelatedPackageVersions:
linux-restricted-modules-3.2.0-29-generic N/A
linux-backports-modules-3.2.0-29-generic N/A
linux-firmware 1.79
Tags: precise running-unity
Uname: Linux 3.2.0-29-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom debian-tor dialout dip lpadmin plugdev sambashare sudo
dmi.bios.date: 12/06/2011
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A24
dmi.board.name: 0T296D
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA24:bd12/06/2011:svnDellInc.:pnLatitudeE4300:pvr:rvnDellInc.:rn0T296D:rvr:cvnDellInc.:ct8:cvr:
dmi.product.name: Latitude E4300
dmi.sys.vendor: Dell Inc.
This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:
apport-collect 1035889
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the Ubuntu Kernel Team.