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From"Ulrich Windl" <>
DateFri, 3 May 1996 09:16:56 +0200
SubjectTwo little fixes for the NTP time interface
Here are two patches for arch/i386/kernel/time.c:

This first patch replaces two magic numbers with symbolic constants.
Maybe MAXPHASE should be the largest possible unsigned value, but 
this is according to the reference implementation.

--- time.c	1996/04/30 22:17:24	1.3
+++ time.c	1996/05/02 19:34:17
@@ -176,8 +176,8 @@
 
 	xtime = *tv;
 	time_state = TIME_BAD;
-	time_maxerror = 0x70000000;
-	time_esterror = 0x70000000;
+	time_maxerror = MAXPHASE;
+	time_esterror = MAXPHASE;
 	sti();
 }
 
This second patch just #ifdefs away the pentium routines that aren't used
when the APM driver is configured. It is believed that APM can change 
the CPU clock; thus the cycle counter can be wrong.
--- time.c	1996/04/30 22:17:24	1.3
+++ time.c	1996/04/22 21:12:19	1.2
@@ -29,6 +29,7 @@
 
 extern int setup_x86_irq(int, struct irqaction *);
 
+#ifndef	CONFIG_APM	/* cycle counter may be unreliable */
 /* Cycle counter value at the previous timer interrupt.. */
 static unsigned long long last_timer_cc = 0;
 static unsigned long long init_timer_cc = 0;
@@ -82,6 +83,7 @@
 		quotient = 1000000/HZ-1;
 	return quotient;
 }
+#endif
 
 /* This function must be called with interrupts disabled 
  * It was inspired by Steve McCanne's microtime-i386 for BSD.  -- jrs
@@ -271,6 +273,7 @@
 	    
 }
 
+#ifndef	CONFIG_APM	/* cycle counter may be unreliable */
 /*
  * This is the same as the above, except we _also_ save the current
  * cycle counter value at the time of the timer interrupt, so that
@@ -284,6 +287,7 @@
 		 "=d" (((unsigned long *) &last_timer_cc)[1]));
 	timer_interrupt(irq, NULL, regs);
 }
+#endif
 
 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
  * Assumes input in normal date format, i.e. 1980-12-31 23:59:59

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