Garten Eden

#linux #programming #android #online #stuff

Get rid of Fast TSC calibration failed

Those among you who compile their own kernel know the bootup message
Fast TSC calibration failed.
which is not visible when you use Ubuntu’s kernel though.

At the end of the day it is a fully harmless message which only purpose is to inform you that the first attempt (via TSC) of reading the system’s clock rate failed. The next method (which is more appropriate for multi core systems) leads to success.

Silent Boot

There are two options now. Either one instructs the kernel via boot parameter to load the right method* straightforwardly (acpi_pm) or one simply disables the message.

I chose the latter and I agree with kernel hacker Paul Bolle who decided to downgrade this rather unimportant notice from the status of error (pr_err) to the status of an information which by default are not visible n the bootup process.

Patch

Finally the corresponding patch looks like (tested with Kernel 3.15.6):

diff -rupN a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
--- a/arch/x86/kernel/tsc.c	2014-07-09 20:21:40.000000000 +0200
+++ b/arch/x86/kernel/tsc.c	2014-07-16 12:57:28.639510526 +0200
@@ -618,7 +618,7 @@ static unsigned long quick_pit_calibrate
 			goto success;
 		}
 	}
-	pr_err("Fast TSC calibration failed\n");
+	pr_info("Fast TSC calibration failed\n");
 	return 0;
 
 success:

fast-tsc-calib-failed.patch (386B text/x-patch)

Your system should now boot without this message.


*The probing methods of the current system can be determined with:

cat /sys/devices/system/clocksource/clocksource0/available_clocksource

Then you can add it as a parameter to clocksource= in the GRUB_CMDLINE_LINUX line in /etc/default/grub.

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