Hi: that is the output from 'uname -a'. The CPU is a Celeron D (Pentium 4) but the OS, slackware 7.1 is too old and does not recognize it. How could I do to make uname print a meaningful name? I think it should say i686.

No way.

Ok. Now I must run a script that builds a new kernel module for the GPU. What happens if, some time in the future, I change the kernel? Should I run the script again?

A more general question is: what happens when I build some piece of software and then I change the kernel? Should I recompile that piece of software?

If you realize what a kernel modules is, the answer should become obvious. And the answer is probably available in that driver's documentation.

It depends if/how this piece of software is linked to the kernel itself or the kernel headers. Again, you could find an answer in the relevant documentation.

OK. By the way: in my hard disk linux partition I have both /lib/modules/2.6.21.5/ and /lib/modules/2.6.21.5-smp. As the kernel I run is smp, I guess only the drivers in /lib/modules/2.6.21.5-smp are used by the system. Am I right?

yup

If I may quote myself, I honestly don't see how uname can't find the machine name. Hasn't the Intel CPU's from Pentium I onwards a CPUID instruction?

The kernel 2.2.16 doesn't know the machine architecture i686.

Funny, that's the Slackware release I started with. Thirteen years ago.

But is does know the CPUID instruction.

You might consider looking at what the CPUID instruction actually does? [1] [2] [3] [4]

It returns Type, Family, Model, and Stepping ID in the AX or EAX register. Family= 6 for my Intel processor.

What makes you think that uname uses CPUID?

Are you absolutely, positively certain that your Celeron D is Family 6 and not Family 'F' (15)?

Read pages 19 and 20 of http://www.microbe.cz/docs/CPUID.pdf and tell us what family your Celeron D is.

And then read pages 5, 6, 7 and 8, and tell us how kernel 2.2.16 would have seen into the future to know what hadn't happened yet.

You're right. My Intel Celeron D is a Prescott (codename) and its family is 15. OK. Now let me tell you a little story. I tried to install the NVIDIA driver under slackware 7.1 and the installer refused to go on because it used the uname command to know the processor type and uname did not provide the necessary information. I had to write a uname script to deceive the installer and make it go on.

In a well conceived operating system, everything should be downwards compatible. So that if I have a program written in 1985, running under an O.S. written in 2000, in a machine built in 2010, there will be no problem at all. To give just an example, I have a chess program from precisely 1985 and it runs OK in any modern machine under Windows XP.