Enable HPET clocksource for Ztdummy

Hi, i’m using Asterisk with C2D cpus loading the kernel (centos 5.1 2.6.18)with clocksource=HPET.
It’s very stable and works great (about 20 installations).

Now i’d like to set ztdummy to works using hpet (as suggested by developers), but looking the code of ztdummy.c, it requires kernel 2.6.22
/* The symbol hrtimer_forward is only exported as of 2.6.22: */

Looking into the /usr/src/linux dir, there’s a hrtimer.h with the function hrtimer_forward.
It’s safe to patch the ztdummy.c to request a kernel 2.6.18 (the centos kernel) and not a 2.6.22?

Sorry for my bad english, thanks at all