Re: [RFC][PATCH] linux-2.6.3-rc2_ia64-cyclone_A0

From: David Mosberger <>
Date: 2004-02-13 11:14:47
>>>>> On Wed, 11 Feb 2004 19:22:21 -0800, john stultz <> said:

  John> All, This patch provides access to the cyclone time source
  John> found on IBM EXA based systems (x450 and x455). This is needed
  John> on multi-node systems where the CPU ITCs are not synchronized,
  John> causing possible time inconsistencies.

  John> I tried my best to properly follow the time_interpolator
  John> interface, but please let me know if you see any mistakes.

  John> Any comments or suggestions would be greatly appreciated.

It looks mostly OK to me.  Some comments:

 - It seems to me cyclone.c should check whether the SAL ITCdrift flag
   is on and register the cyclone time-interpolator only if it is
   turned on.

 - When accessing iomemory space, please use readX()/writeX().  For

 +	offset = cyclone_timer[0];

   should be:

	offset = readl (cyclone_timer);

 - The formatting is a bit weird.  You can format it for 100 columns
   wide and it would be nice if you could drop all the trailing

 - This:
+	u32 offset;
+	offset = (offset*NSEC_PER_SEC)/CYCLONE_TIMER_FREQ;
   will overflow in about 4.3 seconds.  Not likely to happen but
   it might be safer to declare "offset" as "u64".

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Received on Thu Feb 12 19:16:26 2004

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