Checking linux Kernel for RT-Preempt Patch

Question

How to know whether a particular patch is applied to the kernel? Especially RT-Preempt Patch.

Answer 1

In the case of preempt you can just use uname:

uname -v
#23 SMP PREEMPT RT Fri Oct 16 11:52:29 CET 2012

The string PREEMPT shows that you use a kernel version with the realtime patch.

Some other patches might also changes the uname string. So it might also be a help. If this is not the case you can try to look at your .config. The file could be found in the /boot directory or (if enabled) by using cat /proc/config.gz. Maybe there is also a version in /usr/src/linux (or where you put the kernel sources).

If you found the config file you can grep for specific settings and find out if a patch is used.