Archive for April, 2011

Ubuntu and Wireless-N speed issues

I recently picked up an Intel Ultimate-N 6300 from Amazon for my laptop. I’m at the point where, when I’m moving big files to/from my NAS over the wireless connection, I really need the speed of Wireless N.

Unfortunately, Ubuntu didn’t seem to share my enthusiasm for speed — for some strange reason the card remained “locked” at the 54Mbps speed, even though it saw the 5ghz-band SSID.

Fortunately my fix was just a Google away. An article on had this to say, along with the fix:

The problem seems to be that the iwlagn-driver doesnt work right for every supported chip in N-Mode. So the N-Mode is deactivated by default.

To re-enable the N-mode on your card, run these commands as root:

rmmod iwlagn
modprobe iwlagn 11n_disable=0

If your card works in N-mode, you can make it permanent:

edit /etc/modprobe.d/intel-5300-iwlagn-disable11n.conf


options iwlagn 11n_disable=1


options iwlagn 11n_disable=0

You could also simply delete the file. However, editing is reversible in case the card starts misbehaving.

After doing this, my card is up to 270Mbps and all is good.

Did this work for you? Have a different method? Please feel free to share in the comments below!


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Fix for Alienware M15x “Warning: IRQ not configured – PCI in slot 0D”

Alienware M15x owners may see the following message appear during post:

Warning: IRQ not configured - PCI in slot 0D
  Bus:02, Device:00, Function:01

To resolve this rather cryptic error message, make sure you’re running BIOS version A05 or newer. The current BIOS is A09, and is available at (direct link).



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Upgrading Ubuntu and closed-source VirtualBox editions

If you’re using the closed-source version (the non-OSE) of VirtualBox for virtualization, upgrading your Ubuntu version will likely break your VirtualBox installation. This is because VirtualBox uses dkms to automatically pull in and recompile the kernel modules during a kernel upgrade, but when you upgrade your Ubuntu version, the third-party repository is disabled for compatibility.

What you need to do is re-add the repository line for VirtualBox in Synaptic. This is very easy. It’s important to understand that none of the steps listed here will harm your existing VMs — those files are located in ~/.virtualbox for older installs, and “~/VirtualBox VMs” (and the equivalent on Windows machines) in newer installs. You may want to consider backing those files up somewhere else before starting.

Assuming that your Ubuntu upgrade is already complete, you need to know the nickname for your Ubuntu version. This is easily found at System > About Ubuntu.

Once you’ve found that, simply re-add the correct repository line using the following steps:

Step 1 – Find your version

Go to the VirtualBox download page and find the repository line for your version of Ubuntu.

Although VirtualBox development is kept close to the Ubuntu release schedule, new repository lines may not be immediately available after a new Ubuntu release is launched. Simply check back to that page until they have posted the new repository.

Step 2 – Install dkms

This may be required for other programs, but you will want to make sure dkms is installed to keep the VirtualBox modules up to date after installation. Install dkms using your favorite package manager or enter the following command at a terminal:

sudo apt-get install dkms

(I noticed that VirtualBox 4 installs dkms as a dependency — previous versions may as well. It’s always best to play it safe.)

Step 3 – Enter the repository information in Synaptic Package Manager

Open Synaptic and follow the following menu trees to add the new repository line.

system > administration > synaptic package manager

settings > repositories

Click other software tab

Click add button

Paste your repository line that matches your version, found at the VirtualBox website, here.

Close and click reload.

Step 4 – Install VirtualBox

Now, install the virtualbox-4.0 (or the current version) using your favorite package manager, or enter this at a terminal:

sudo apt-get install virtualbox-4.0

If you experience issues with message related to no key, no signature, or bad signature, refer to the VirtualBox Linux Downloads page for information on resolving that. The messages are generally safe to ignore, though more cautious users may want to install the signing key to make sure the downloads have the correct digital signature.

Questions, comments, and feedback are welcome and appreciated.

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