Enabling amd64v3 Packages on Ubuntu 25.10: A Step-by-Step Guide

If you’re looking to enhance the performance of Ubuntu 25.10 and have a modern 64-bit CPU, you might want to consider enabling Ubuntu’s new amd64v3 packages. These packages, also referred to as x86-64-v3, are optimized to utilize specific instruction sets of the v3 microarchitecture.

Before diving into the installation process, it’s important to note that not all 64-bit Intel and AMD CPUs support these features. To check if your CPU is compatible, the following command can be run in the terminal:

/lib64/ld-linux-x86-64.so.2 --help

Scroll through the output to find if x86-64-v3 is listed as supported. If it is, you can proceed. However, if it is not supported, using these packages will not be feasible for your system.

Keep in mind that while the amd64v3 packages may offer some performance enhancements, they are not guaranteed to provide substantial improvements; benchmarks have shown gains of around ≤1% with more notable increases seen in demanding computational tasks. Moreover, not every software will benefit from these optimized packages. Only the packages in the main repository have v3 versions available in 25.10, which means applications distributed as DEB files, Snaps, Flatpaks, etc., might not take advantage of these enhancements.

Installing amd64v3 Packages

To enable the use of amd64v3 packages, you’ll need to issue some terminal commands:

First, create a configuration file by running:
```
echo 'APT::Architecture-Variants "amd64v3";' | sudo tee /etc/apt/apt.conf.d/99amd64v3
```
This allows APT to fetch the v3 variants of the packages.
Update your package cache using:
```
sudo apt update
```
This will show you a list of available updates for the amd64v3 versions of your installed packages.
If you are comfortable proceeding with the upgrades, run:
```
sudo apt upgrade
```

It is important to note that during this process, you may receive messages indicating that some packages are being "downgraded," but don’t be alarmed as this is a known cosmetic issue that will be resolved in future releases.

Reverting Changes

If using amd64v3 packages causes system instability or you simply wish to return to standard package versions, you can easily reverse this:

Remove the configuration file:
```
nautilus admin:///etc/apt/apt.conf.d
```
Locate and delete the ’99amd64v3′ file from the folder.
Clean up the package list:
```
sudo apt update --list-cleanup
```
Finally, run a regular update to restore any upgraded packages to their standard versions:
```
sudo apt updatesudo apt upgrade
```

As of now, the v3 packages are experimental and limited to the main repository. Canonical plans to introduce broader support for these packages in Ubuntu 26.04 LTS, but always proceed with caution and understand that using these packages may involve troubleshooting.

For more details on amd64v3 packages, refer to the original guide.