Hi, Stap couldn't work on 2.6.28-rc4 due to for_each_cpu macro, see http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=cb56d98e2a7530615899597551db685d68a2e852#patch1 seems to need update autoconf test for this macro or change to another name like stp_for_each_cpu. Regards, Wenji