Using yum to apply kernel modules - architecture questions
 

When I get a kernel update, it drops the installed module for my graphics card driver, kmod-nvidia-304xx from ELRepo. I am confused over how this works and what's happening behind the scenes on my system, which is CentOS 7.1, btw.

I start with a system that works with the module installed.
I update the kernel.
But if I reboot and grub into runlevel 3 (multi-user.target), on the new kernel and try to do,
yum install kmod-nvidia-304xx
I curiously get a "nothing to do" response from yum. It thinks it's already installed it.
But it is only installed on the older kernel, not the newest one.
So to install on the new kernel, I found I can run,
yum erase kmod-nvidia-304xx
and install it (again). And that works.

Erase removes it not only from the kernel, but from my system. So I download the 30 Mb all over again too. This takes awhile. Maybe I will try to use "yum remove" next time.

Did the erase remove it from the former kernel?
It certainly allows it to install it on the new kernel.

Why does yum become confused as to which kernel we're targeting? I would have thought yum would work against the currently running kernel.

Is there a switch I can throw that tells yum to ignore it's own thinking and install it again?
So does this mean I can have only ONE kernel with the kmod-nvidia-304xx module installed?

According to elrepo, the kernel was supposed to carry over this module across kernel updates, but it doesn't do it for me.

Thanks,

Hi needsleep
First The erase removed it from your system. It is not "removed from the former kernel".
Second No it just installs it on your system. It obviously has different libs or whatever which is loaded at runtime for your newest kernel.
Third It does not get confused about kernels but it recognizes different packages especially if they have similar names.
Fourth No.
Fifth Each Kernel will work only with its designated module.
Sixth Not sure how Cent OS 7.1 handles dependencies, as I use Fedora.