time: Workaround gcc loop optimization that causes 64bit div errors

Early 4.3 versions of gcc apparently aggressively optimize the raw time accumulation loop, replacing it with a divide. On 32bit systems, this causes the following link errors: undefined reference to `__umoddi3' undefined reference to `__udivdi3' The gcc issue has been fixed in 4.4 and greater. This patch replaces the accumulation loop with a do_div, as suggested by Linus.

John Stultz committed 16 years ago

Commit c7dcf871 parent 2be1f3a1 file · +4 −3Browse files

Showing the changes to kernel (1 of 1 file). Show all

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kernel/time/timekeeping.c+4−3

@@ -710,9 +710,10 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift) · 709 unmodified lines
710	710	/* Accumulate raw time */
711	711	raw_nsecs = timekeeper.raw_interval << shift;
712	712	raw_nsecs += raw_time.tv_nsec;
713		− while (raw_nsecs >= NSEC_PER_SEC) {
714		− raw_nsecs -= NSEC_PER_SEC;
715		− raw_time.tv_sec++;
	713	+ if (raw_nsecs >= NSEC_PER_SEC) {
	714	+ u64 raw_secs = raw_nsecs;
	715	+ raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
	716	+ raw_time.tv_sec += raw_secs;
716	717	}
717	718	raw_time.tv_nsec = raw_nsecs;
718	719