Broken Kernel from Terasic's website

I am using the Altera Cyclone V DE1 SoC and am booting Linux with Ubuntu Linux Desktop image provided on Terasic’s website. When I type “uname -r” into the terminal, it says the kernel version, which ends with “-dirty”. “Dirty” means that the kernel has not yet been compiled or is broken. Does this happen to you?

It means that the kernel source you compiled from has been modified and the modifications were not checked in.