Ingo, Maciej,
it seems I found a bit strange code snippet in apic_32.c:setup_boot_APIC_clock.

We set local_apic_timer_verify_ok = 1 before checking the results. I think

the following patch make sense. Please take a look on.
---

We set lapic flag that clocksource calibration is

fine too early. Fix it.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

---
Index: linux-2.6.git/arch/x86/kernel/apic_32.c

===================================================================

--- linux-2.6.git.orig/arch/x86/kernel/apic_32.c	2008-07-13 15:25:20.000000000 +0400

+++ linux-2.6.git/arch/x86/kernel/apic_32.c	2008-07-13 15:31:03.000000000 +0400

@@ -489,8 +489,6 @@ void __init setup_boot_APIC_clock(void)

 		    calibration_result / (1000000 / HZ),

 		    calibration_result % (1000000 / HZ));
-	local_apic_timer_verify_ok = 1;

-

 	/*

 	 * Do a sanity check on the APIC calibration result

 	 */

@@ -504,6 +502,8 @@ void __init setup_boot_APIC_clock(void)

 		return;

 	}
+	local_apic_timer_verify_ok = 1;

+

 	/* We trust the pm timer based calibration */

 	if (!pm_referenced) {

 		apic_printk(APIC_VERBOSE, "... verify APIC timer\n");

--

[Cyrill Gorcunov - Sun, Jul 13, 2008 at 03:37:34PM +0400]

| Ingo, Maciej,

|

| it seems I found a bit strange code snippet in apic_32.c:setup_boot_APIC_clock.

| We set local_apic_timer_verify_ok = 1 before checking the results. I think

| the following patch make sense. Please take a look on.

|

| ---

| We set lapic flag that clocksource calibration is

| fine too early. Fix it.

|

| Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

| ---

|

| Index: linux-2.6.git/arch/x86/kernel/apic_32.c

| ===================================================================

| --- linux-2.6.git.orig/arch/x86/kernel/apic_32.c	2008-07-13 15:25:20.000000000 +0400

| +++ linux-2.6.git/arch/x86/kernel/apic_32.c	2008-07-13 15:31:03.000000000 +0400

| @@ -489,8 +489,6 @@ void __init setup_boot_APIC_clock(void)

|  		    calibration_result / (1000000 / HZ),

|  		    calibration_result % (1000000 / HZ));

|

| -	local_apic_timer_verify_ok = 1;

| -

|  	/*

|  	 * Do a sanity check on the APIC calibration result

|  	 */

| @@ -504,6 +502,8 @@ void __init setup_boot_APIC_clock(void)

|  		return;

|  	}

|

| +	local_apic_timer_verify_ok = 1;

| +

|  	/* We trust the pm timer based calibration */

|  	if (!pm_referenced) {

|  		apic_printk(APIC_VERBOSE, "... verify APIC timer\n");
Letme clarify a bit situation why I propose this path (it's not that

clear from its description).
While calibrating apic timer we use different 'flags' signaling if it

was success/fail. On 64bit platform lapic_timer_setup() does check

for CLOCK_EVT_FEAT_DUMMY bit which is set by default and cleared on

successfully calibrated timer. So 64bit is fine now. On 32bit we

use a different approach - local_apic_timer_verify_ok flag _BUT_

as I see it being set too early _before_ calibration result is checked

so we could have the following - kernel reports user that APIC timer

is too slow and disabled but local_apic_timer_verify_ok remains set

to 1 instead of 0.
		- Cyrill -

--