I've got a 32-bit Ubuntu installation running on 64-bit hardware. Now that multi-arch has been implemented, I would like to switch to 64-bit without having to reinstall the OS.
This is one of the user stories addressed by the spec:
Shawn installed his system using the 32-bit version of Ubuntu, but his hardware is 64-bit and he wants to switch over. He manually installs the amd64 versions of dpkg and apt, replacing the i386 versions and changing which architecture is used as the default; then he installs the amd64 ubuntu-minimal package; then he installs the amd64 ubuntu-desktop package. Over time the remaining i386 packages are replaced automatically on upgrade.
However, when trying to follow the instructions in there, I cannot find any 64-bit version of dpkg or apt.
Did this user story got implemented in a different way in the final spec, or do I need to do something differently?
In short, how can I switch my 32-bit installation to 64-bit?
Such an approach is very complicated, and is unlikely to ever result in all your packages being the
amd64version instead of the
i386version. Only packages that actually receive upgrades will likely be changed in architecture, and probably only if no other packages not being upgraded rely on their being of the
i386architecture. Since some packages will not receive any updates throughout the entire support cycle of your Ubuntu release, you will likely never have a fully
amd64system using such a technique. Furthermore, there is certainly no official support for such an approach.
You would be well-advised to instead replace your existing Ubuntu system with a new, 64-bit installation.
However, if you do wish to attempt this technique, you will have to manually download the
apt. You can find them at the
dpkgin Ubuntu and
aptin Ubuntu pages on Launchpad--expand the latest version under "The Oneiric Ocelot" that is marked as release, security, and/or updates (but you probably don't want a version marked only proposed and/or backports, if there ever is one). Then download the
amd64. Specifically, the files you'll want are: this one for
dpkg(and the others listed, too, if you have those packages installed) and this and this and this and this and this for
Before you do anything with these files, you should make sure to back up all important documents in your installed Ubuntu system and any other important files (e.g., music, ebooks, videos), because it is rather likely that attempting this technique will backfire badly and leave your Ubuntu system completely unusable.
You can install all these packages by putting them in a folder that contains nothing else (suppose the folder is called
debsand is inside your
Downloadsdirectory), and then running this command:
Of course, once you've installed them, they won't actually run, because their executables are 64-bit and your 32-bit Ubuntu system is running a 32-bit kernel (which will only run 32-bit executables). In fact, they might not even finish installing, as they might have post-install scripts that invoke their unrunnable 64-bit executables.
There are various ways of attempting to install a 64-bit kernel onto a 32-bit system, but they are all extremely complicated, so instead I recommend that you boot from a 64-bit Oneiric live CD (which itself runs a 64-bit kernel), chroot into the installed Ubuntu system, and use the recently installed 64-bit
dpkgto install a 64-bit kernel.
Here are specific instructions for doing that...but please do not take this to mean that I'm saying it will work. I have not attempted this. (I have chrooted into installed Ubuntu systems from live CD's and performed package management and other operations, but I have not attempted the cross-architecture operations suggested here.)
In your installed Ubuntu system, open a Terminal window (Ctrl+Alt+T) and run
mount | grep ' on / '(by pasting it into the Terminal and pressing enter). You should see something like
/dev/sda2 on / type ext4 (rw,errors=remount-ro,commit=0). The part you're interested is the device name before
on(in this example, it's
/dev/sda2). Remember that, or write it down.
Step 1 gave you the device name of the
/partition. If you have a separate
/bootpartition, then you'll need to know the device name for that as well. So in that case, run
mount | grep ' on /boot '. You'll see something like
/dev/sda1 on /boot type ext2 (rw). Remember or write this down as well.
Boot from an Oneiric amd64 (i.e., 64-bit) live CD and select "Try Ubuntu" rather than "Install Ubuntu".
Go into a web browser and make sure that Internet connectivity is fully functional. If it isn't, set it up.
Open a Terminal window and run
sudo mount /dev/sda2 /mnt(replace
/dev/sda2with the device name you got in step 1, if different).
If your installed system has a separate
sudo mount /dev/sda1 /mnt/boot(replace
/dev/sda1with the device name you got in step 2, if different).
Now, run these commands to chroot into your installed system:
ping -c 4 launchpad.netto see if Internet connectivity works fully from within the chroot. You're hoping for something like this:
If, instead, you were unable to transmit or receive packets, then you'll have to set up Internet connectivity in the chroot. To do that, run these commands (to leave the chroot, copy the relevant configuration files from the live CD system into the chroot, and re-enter the chroot):
While generally you should stop this process if there is an error, don't worry if the first and/or second of those four commands fail, provided that the specific way in which it fails is by telling you that
/mnt/etc/hosts) does not exist.
The chroot back in and try again:
Run these commands to make your chrooted environment fully ready to use:
If you haven't installed the
.debfiles for the 64-bit versions of
apt, so do now. If you did install them but there were configuration errors, run
dpkg --configure -ato fix them. (Hopefully that will work...it might be better to wait to attempt to install them until you're in the live CD environment, in case installing the 64-bit
dpkgwhile booted into the installed system leaves
dpkgin an unusable state.)
With the 64-bit versions of
aptinstalled, assuming that they will automatically install 64-bit packages, you can now remove all your 32-bit kernels and install a 64-bit kernel. To remove your 32-bit kernels, run
dpkg -l | grep linux-. This lists installed packages that start with
linux-. You're more specifically interested in packages that start like
linux-headers. Remove these files with
apt-get purge ...where
...is replaced with a space-separated list of the packages you're removing.
Now reinstall the packages you removed. (Actually, for packages that contain version numbers in the package name, like for example
linux-image-3.0.0-13-generic, you only need to install the latest versioned package names.) Do this by running
apt-get install ...where
...is replaced with a space-separated list of the packages you're installing.
Update the boot loader configuration, unmount some devices, and leave the chroot:
If you ran
sudo cp /mnt/etc/resolv.conf /mnt/etc/resolv.conf.oldand it did not fail, then now run
sudo cp /mnt/etc/resolv.conf.old /mnt/etc/resolv.conf.
If you ran
sudo cp /mnt/etc/hosts /mnt/etc/hosts.oldand it did not fail, then now run
sudo cp /mnt/etc/hosts.old /mnt/etc/hosts.
If your installed system has a separate
/bootpartition, unmount that:
sudo umount /mnt/boot
Unmount your installed system's
sudo umount /mnt
Leave the Terminal window (run
exit), then reboot (or shut down) the live CD system and boot into the installed system.
See if the system is usable and running a 64-bit kernel (
uname -mshould say the architecture is
There might well be additional packages you need to install, such as
ia32_libsand/or the 64-bit version of
libc6, for this to work. For some of them, you might be informed you need them when attempting to install the 64-bit version of
apt. For others, you might not be informed.
(The above instructions for chrooting and operating in the chrooted environment are based in significant part on this related but different procedure and also on some Launchpad Answers posts of mine, especially #6 here and #6 here. And special thanks to Caesium for pointing out that the 64-bit
aptexecutables won't run on a system running a 32-bit kernel.)