I have an HP Notebook and I installed Ubuntu 16.04 beside Windows 10. I checked for Additional Drivers, and I was shown (Processor microcode firmware for AMD CPUs from amd64-microcode). When I select it, I am shown a message that tells me that the driver is proprietary, and that Ubuntu can't review nor update it.
I understand this, but I don't know if using such Updater affect my privacy, or if it is just a matter of quality and getting updates from a company other than Ubuntu.
This is not a driver. This is a CPU microcode updater.
It installs proprietary microcode released by AMD.
You get this message because Canonical does not control that microcode.
The same microcode is implemented in your BIOS. Ubuntu updates it if it is newer than the one in your BIOS.
It is quite safe to use the updater.
The question is very similar to this one.
You can check if the updated really installs some microcode by running
dmesg | grep microcode
You will see if some microcode is loaded. If not, then it does not matter if you install it or not.
Ubuntu is trying to warn you about a difference between proprietary software and Free and Open-Source Software (FOSS).
Note: These are two extremes and other philosophies and licenses exist.
In many Linux ecosystems, FOSS is the adopted mentality. Here, code is shared so that others can freely modify and make improvements to the code. People are encouraged to use the software for whatever reason they see fit.
When Ubuntu adds free and open-source software, the maintainers and many smart people are able to review the code, find bugs, and implement patches or fixes to issues. This gives Ubuntu an advantage in that they can have more control over the quality of the software available in the repositories (ie: apt).
Sometimes a company wants to hide how something works. There are many reasons as to why a person or company might feel the need to do this, but in such a situation, the code is proprietary. This means that it's compiled or obfuscated in such a way that Ubuntu maintainers and others have no way of reading through the code to determine if the code is high quality, or everything it can/will do. It also means that if the newest kernel has issues with the proprietary code, we have to wait for the owners of the code to make changes, instead of allowing the community to implement the changes.
Today, we have more and more availability to use FOSS and I recommend that you weigh the risk/benefit of running proprietary software. It really depends on your goals, and the state of the open software, but the reality is that if you run proprietary software, nobody can tell you 100% what the software does or is capable of doing. You can reverse engineer and trace what it's currently doing, but to be 100% is not possible from my understanding.
That being said, I do believe that it is in the best interest of companies such as AMD to provide 'honest' software, because anything they do would probably eventually be discovered.
