It is important that base system be completely GPL-free, which is one of the main reasons the CLANG compiler is being developed.
When thinking GPL vs BSD License, in many situations the "free"-ness is the same.
For all intents and purposes, for "personal use" there is not much of a difference between GPL and BSDL.
When comparing GPL and BSD License, it makes sense to talk of the situation where the difference is most emphasized. So a good scenario where the difference is most emphasized is this:
CompanyXYS has a great idea for a new product.
They decide to make an appliance they will sell and distribute.
They want an open source operating system.
They will have their new awesome proprietary software running on top of it.
I have an article that covers this:
Differences between the BSD/FreeBSD Copyrights and the GNU Public License (GPL)
If they go with a BSDL/MIT license, their costs could be a lot lower than if they go with GPL for a few reasons.
1. GPL requires you redistribute the source. Yes, this takes time and money. Do you need a web site or just someone responding to email?
2. GPL requires that you release your changes as GPL as well. This can take away sales and be a competitive disadvantage. Maybe you have to limit yourself to selling support and services because you can't sell your product as you have to give it away for free.
3. You have to give up a lot of you Intellectual Property (IP) as it touches GPL and so everyone can use.
4. You almost have to hire a lawyer to make decisions on what can be proprietary and what can't.
5. You have to train and educate your developers on when they can and can't link to GPL.
6. Failure to comply leaves you open to a lawsuit that could be quite expensive and even if you win, ruins your profits and ends your business.
The costs of the GPL in an enterprise appliance can continue to pile up. The less GPL you have, the less the cost.
If you go completely GPL free, you don't have any of the above costs. You can just distribute the OS without a concern in the world for licensing. You don't have distribute the code, call a lawyer, worry about a lawsuit, or anything.
This is why Apple used a lot of BSD source. This is why some key components of Android were replaced with GPL equivalents. This is why you can find BSD software in things like TVs.
So yes, it is very important to have a list of what software is in the base system that is not GPL.
GPL =
Communism (not the false negative connotation of bad countries with dictators that cause wars, but the actual dictionary meaning of the word: the community owns the software and the software is shared in common...click the link read the dictionary meaning and please no troll-ing)
BSD =
Communism or
Capitalism
It is because the BSD License goes both ways, that in the situation described above the company distributing an appliance is set free. This company can maintain their capitalism while still participating in the community and contributing code back that may not be proprietary. Apple does this with FreeBSD, I hear.
By the way, is there such a list of what remains in the base system that is GPL? (Because I found this post looking for that list.)