[tlug] Not understanding how updated kernels work

[Dave M G <martin@example.com>]

TLUG,

The other day, Ubuntu gave me a notice that there were some updates I 
needed to install. I went ahead and updated everything, and then at the 
end it said I needed to reboot in order for the updates to take effect.

I rebooted, and discovered that X would not start. I'm helpless in a 
command line interface, so this was quite a problem.

It wasn't a complete surprise, mind you. My video card is very new, and 
I had to get drivers direct from Nvidia in order to get X working at all.

I tried running the Nvidia driver install utility again, but it 
complained it could not find nvidia.ko in the right place or something, 
and wouldn't work.

The basic short story is that the kernel was upgraded from 2.16.20 to 
2.16.21, and the new kernel doesn't like my graphics card or something.

Happily, I learned that through GRUB I can just boot to my previous 
2.16.20 kernel, and I'm back in business.

But then another set up updates showed up, and that's when I got a 
little confused.

When I download more updates on a previous kernel, do the updates apply 
only to that kernel? I understand that updates to applications and 
things will impact the applications only. But what if, for example, 
there's something that affects the kernel, like an updated driver for a 
USB device?

Will the update be applied to the kernel I'm running now? To the latest 
kernel? To all kernels?

I'm wondering if I'm going to cause confusion on my system by staying 
with a kernel that is working rather than the latest one they've issued.

--
Dave M G