How do I force Kubuntu 12.10 to boot in 32-bit mode (Linux 3.2.0-34-generic-pae)?

Question

Just upgraded from 12.04 to 12.10, on my ancient 32-bit Dell Latitude C-400 laptop.

After the install, I restarted my machine as directed by the OS and got a blank screen. The computer appeared to be running fine, just no display.

Booting in GRUB gave me the option of two versions (as well as recovery modes for both):

1. Linux 3.5.0-45-generic
2. Linux 3.2.0-34-generic-pae

Apparently 3.5 is the 64-bit version, and 3.2 is the 32-bit version. When I choose 3.2.0, the system completes the boot sequence as it should, complete with functioning video display.

How do I force Kubuntu to boot in Linux 3.2.0? If it's as simple as changing the order of the versions listed in GRUB, how do I do that?

Thanks in advance.

Answer 1

I don't know about Linux 3.5.0-45-generic being 64-bit. That would not possible if your Laptop only supports 32-bit. Putting that aside, your question is about how to set default boot entry. Take a lookt at Grub Customizer. There is one good tutorial here: How do I change the GRUB boot order?. The accepted answer there can be a bit confusing. You can just follow the second answer, which I paste here:

You can also change the grub default boot entry from the command line without having to install any additional tool. This won't change the order in the list but it will allow a different OS to boot by default, which sounds like what you may want anyway.

First, make a backup copy of /etc/default/grub. In case something goes wrong, you can easily revert to the known-good copy.

sudo cp /etc/default/grub /etc/default/grub.bak

Then edit the file using vim or the text editor of your choice.

sudo vim /etc/default/grub

Find the line that contains GRUB_DEFAULT=0 and set it to GRUB_DEFAULT=x where x is the index of grub menu item to which you would like to boot to by default. Note that the menu items are zero-indexed. That means that the first item in the list is 0 and that the sixth item is actually 5. So to boot to the sixth item in the list, the line would read GRUB_DEFAULT=5.

Additionally, if you want to use a kernel in the "Previous Linux Versions" menu, you'll want to change GRUB_DEFAULT=0 to GRUB_DEFAULT="2>x" (make sure to include the quotations), where x is the placement of the old kernel on the sub-list (assuming the "Previous Linux Versions" is third on the main list). Remember that the list always begins counting at 0.

Then build the updated grub menu.

sudo update-grub