Unless you plan on dying very soon, I bet you will see your "no-reboot" OS ;)
https://github.com/dynup/kpatch
(included in the kernel tree since Linux 4.0)

https://en.wikipedia.org/wiki/Kpatch

Yes you will be able to do a clean install of the windows 10 upgrade after the first upgrade. Source,
http://www.microsoft.com/en-us/windows/windows-10-faq

How do they know if your system is the same source? dunno. But windows 10 oem will be bound to your systems motherboard.

"WARNING: Use with caution! Kernel crashes, spontaneous reboots, and data loss may occur!"

Lets just ignore that part.
Yes. The problem is that they recreated the whole audio stack, to reduce latency, improve performance, and all that. They did the same with the Bluetooth stack as well. And now, old hardware may not function properly until required drivers are developed / fixed.

Where in my post did you read me stating it was ready to use in production right now?

Thanks. So, I will have to perform a Windows 7 => Windows 10 upgrade _once_, while the one-year offer period is still on? But after that, I am free to clean-install it on that same PC as many times I want?

One more important question, just to be sure: does it invalidate my existing Windows 7 license? So if I decide to go back to Windows 7 (installing it from scratch), I can still validate it fine? And later clean-install Windows 10 again, if it comes to that?

I presume it doesn't invalidate the earlier license (because buying the cheap Windows 8 Pro upgrade license didn't invalidate my Windows 7 which I am using now), but just want to be sure if there is some hidden small print, as if that this free offer means I am replacing my Win7 license with a Win10 license.

I know you're speaking of GOG as a service and the vast library of games working in general, but I also hope this means we might get a DirectX 12 update for Witcher 3 if you're really embracing Windows 10.

Damn I am glad I read that FAQ before reserving Windows 10, because it made me realize that apparently I am actually eligible for Windows 10 Pro.

My Windows 7 is only Home Premium, but IIRC the Windows 8 upgrade license I have is for the Pro version. The latter should let me get a free Windows 10 Pro version, if I read correctly.

Wow, it seems that Windows 8 license wasn't a completely worthless (albeit cheap) purchase after all? Unfortunately that apparently means I now need to reinstall Windows 8 again, and then make that Windows 10 reservation? Or is there some optional way to convince the Microsoft robot that I am eligible for the Windows 10 Pro, without a Windows 8 reinstallation???

Yes you will be able to install clean install of the windows 10 iso on the same upgraded system via clean install.
You will be able to revert to your previous install oem OS if you have your original USB or DVD from the manufacturer.

But if your worried about windows 10 do the upgrade only ... When install the upgrade there will be an option to save your older windows 7 or 8 partition. Like a backup should thing not work for you in windows 10 you can revert back.

You can find more details at the MS sites.. You can google the information if your into tech details.

I'm going to upgrade my windows 7 home premium to windows 10. Then I'll delete my partitions and reinstall windows 10 iso. The only difference with the W10 Retail is you can transfer your OS to a new system. OEM is bound to current systems motherboard and oem OS 7 or 8.

http://answers.microsoft.com/en-us/windows/forum/windows_7-windows_install/how-exactly-does-windows-7-retail-vs-oem/fae7b2ab-c530-45e6-aeb3-cc55cf7b9231

How easy is it to transform a pre-DirectX 12 game into a DirectX 12 game? Just push a few buttons, or reprogram big parts of the game engine? I have no idea, but just thinking about the feasibility of your suggestion. After all, I presume lots of the Witcher 3 programmers are increasingly being moved to e.g. Cyberpunk 2077 programming.

Yes, designed by my former employer... :) Dunno if you read my whole post, but I mentioned the following ...

"There are at least two different solutions available for the Linux operating system that provide some of this functionality but it is more or less limited to being able to upgrade the kernel and drivers in-place to avoid an immediate reboot and tacked on to the existing Linux design rather than designed in from the ground up. As such it is not on the same scale or scope as the features provided in Minix 3 for example. Nonetheless it is a good start. :) "

While I did not outright name these technologies, I was referring to both ksplice and kpatch. These both provide some of the functionality I seek but in a limited way that isn't entirely automatic but rather requires administrative effort/expertise. I have such expertise of course, but the vision that I have in my mind of an OS kernel that I'd like to have is one that is built from the ground up to have reliability and stability as core parts of the design in a sense that Minix 3 was designed, where the system can be somewhat autonomous to a degree (there are limitations). A driver could get updated in the background by administrative automated processes and no reboot is needed, but perhaps the driver crashes so the reincarnation server (in Minix parlance) restarts it to have it crash again a few times, at which point it automatically restarts the previous driver that worked and sends an administrative alert or auto-files a bug report in the background to the driver developer/vendor etc. Something as automatic as possible, integrated into mainstream systems. Picture Windows doing this and all existing Windows users just getting say Windows 11 and drivers automatically restart when they crash with no computer geek expertise needed, Grandma has no idea it even happens, never needs to reboot for an update nor to open a command prompt and run cryptic commands or know any technical stuff.

Nothing exists like that right now that I'm aware of, although the research being done on Minix while at a technical geek level currently seems like a step in the right direction at the OS design level at least. What would really be nice would be to see a similar approach taken within a future design overhaul of Linux. Having said that though, I'm not fond of the microkernel approach used by Minix either so it's not clear how these features could be done in Linux with the same level of protection the Minix approach has through unprivileged processes used for everything and utilizing multiple protection rings (Linux uses only ring 0 and 3 not considering hypervisors).

In short, I'm having a pipe dream fantasy that is rather unlikely to see in an end consumer desktop operating system any time in the next 10-20 years, but hey one can dream!

In the mean time on the Linux side of things one can utilize ksplice or kpatch for some of this functionality and it does provide some useful benefits but it's not the same thing by far. :) Imagine a world where your nVidia or AMD video driver can't trigger a bug that causes the driver to inadvertently scribble all over random kernel memory until the computer reboots. That's what I'm looking for. :) Current general purpose operating systems just don't do that sadly. :)

Woops, I obviously missed that part!
Thanks for the in-depth explanation ;)

That's bad and you should feel bad.

Also, it's probably busy trying on belts and will be back when it's good and ready.

I have noticed that some of the games are missing icons in the Windows 10 Start Menu (e.g. King Quest 1-7).