diff --git a/sys/conf/options.i386 b/sys/conf/options.i386
index c76983d0f592..40915422f082 100644
--- a/sys/conf/options.i386
+++ b/sys/conf/options.i386
@@ -36,7 +36,6 @@ PAE			opt_global.h
 
 CLK_CALIBRATION_LOOP		opt_clock.h
 CLK_USE_I8254_CALIBRATION	opt_clock.h
-CLK_USE_TSC_CALIBRATION		opt_clock.h
 TIMER_FREQ			opt_clock.h
 
 CPU_ATHLON_SSE_HACK		opt_cpu.h
diff --git a/sys/conf/options.pc98 b/sys/conf/options.pc98
index 4b07bc09e773..413f12eaef91 100644
--- a/sys/conf/options.pc98
+++ b/sys/conf/options.pc98
@@ -33,7 +33,6 @@ KVA_PAGES		opt_global.h
 
 CLK_CALIBRATION_LOOP		opt_clock.h
 CLK_USE_I8254_CALIBRATION	opt_clock.h
-CLK_USE_TSC_CALIBRATION		opt_clock.h
 TIMER_FREQ			opt_clock.h
 
 CPU_BLUELIGHTNING_3X		opt_cpu.h
diff --git a/sys/i386/conf/NOTES b/sys/i386/conf/NOTES
index 3f7e97a2b13f..3c3258a03140 100644
--- a/sys/i386/conf/NOTES
+++ b/sys/i386/conf/NOTES
@@ -238,17 +238,16 @@ options 	DEVICE_POLLING
 
 # The following options are used for debugging clock behavior only, and
 # should not be used for production systems.
-#
-# CLK_CALIBRATION_LOOP will run the clock calibration loop at startup
-# until the user presses a key.
 
+# CLK_CALIBRATION_LOOP causes clock calibration to be run in a loop at
+# startup until the user presses a key.  (The i8254 clock is always
+# calibrated relative to the RTC (mc146818a) and this option causes the
+# calibration to be repeated.)
 options 	CLK_CALIBRATION_LOOP
 
-# The following two options measure the frequency of the corresponding
-# clock relative to the RTC (onboard mc146818a).
-
+# CLK_USE_I8254_CALIBRATION causes the calibrated frequency of the i8254
+# clock to actually be used.
 options 	CLK_USE_I8254_CALIBRATION
-options 	CLK_USE_TSC_CALIBRATION
 
 
 #####################################################################
diff --git a/sys/pc98/conf/NOTES b/sys/pc98/conf/NOTES
index 819d46ed3a3d..51b74eeefdc5 100644
--- a/sys/pc98/conf/NOTES
+++ b/sys/pc98/conf/NOTES
@@ -212,17 +212,16 @@ options 	DEVICE_POLLING
 
 # The following options are used for debugging clock behavior only, and
 # should not be used for production systems.
-#
-# CLK_CALIBRATION_LOOP will run the clock calibration loop at startup
-# until the user presses a key.
 
+# CLK_CALIBRATION_LOOP causes clock calibration to be run in a loop at
+# startup until the user presses a key.  (The i8254 clock is always
+# calibrated relative to the RTC (mc146818a) and this option causes the
+# calibration to be repeated.)
 options 	CLK_CALIBRATION_LOOP
 
-# The following two options measure the frequency of the corresponding
-# clock relative to the RTC (onboard mc146818a).
-
+# CLK_USE_I8254_CALIBRATION causes the calibrated frequency of the i8254
+# clock to actually be used.
 options 	CLK_USE_I8254_CALIBRATION
-options 	CLK_USE_TSC_CALIBRATION
 
 
 #####################################################################