[PATCH 2/3] ARM: sched_clock: support 64-bit counters

Russell King - ARM Linux linux at arm.linux.org.uk
Fri Mar 22 07:09:07 EDT 2013

On Thu, Mar 21, 2013 at 10:02:57AM -0400, Christopher Covington wrote:
> To be more precise, architected timers are anywhere between 56 and 64 bits
> wide, zero-extended to 64-bits. See section B8.1.1 of the ARM ARM rev C.b. I
> don't know if the code really needs to change until someone has a need to
> distinguish more finely between timers, but if you're using access size as an
> approximation for counter width, I feel like it at least deserves a mention in
> the comments.

If the counter is such that it doesn't produce a full 64-bit nsec value
from sched_clock(), then it needs to be extended to 64-bit.

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