Eli Carter writes:
> Russell, I know that at least the EBSA285's timer1_gettimeoffset() needs
> some attention to fix a time going backward problem.
I know about this, which is what started me looking at what x86 does,
and I am firmly of the conclusion that x86 is buggy as it stands.
I believe that we can, instead of having a per-machine fix on ARM, have
a generic fix. At the moment, I haven't worked out exactly what this
generic fix would be.
> The problem is only going to occur if gettimeoffset has not been called
> in the past 10ms. Once 10ms has passed, either jiffies has changed, or
> count will have passed count_p.
My concern with the x86 fix is what if 9.9999999999ms has passed since the
last timer tick, and we got the timer tick after we disabled interrupts and
entered do_gettimeofday. This can lead to the tests in there miscorrecting
IMHO. You won't see it with an infinite loop reading the time of day...
I'll re-read your mail in more depth later tonight. Appologies if this
reply appears to be a little early.
--
Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux
http://www.arm.linux.org.uk/personal/aboutme.html
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This archive was generated by hypermail 2b29 : Fri Mar 23 2001 - 21:00:12 EST