Date: Thu, 13 Jan 2000 22:48:11 GMT From: stenn@whimsy.udel.edu To: FreeBSD-gnats-submit@freebsd.org Subject: kern/16113: STABLE kernel page fault changing the timer frequency Message-ID: <200001132248.WAA01548@howland.udel.edu>
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>Number: 16113
>Category: kern
>Synopsis: Kernel page fault panic using sysctl to change timer frequency
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Jan 13 14:50:01 PST 2000
>Closed-Date:
>Last-Modified:
>Originator: Harlan Stenn
>Release: FreeBSD 3.4-20000105-STABLE i386
>Organization:
>Environment:
3-STABLE (not 2-STABLE or -CURRENT)
>Description:
Wrote a perl script to wiggle the timer frequency, based on ntpd's
/etc/ntp.drift file and input from PHK. It seems to work fine on
2-STABLE and -CURRENT, but it panics a 3-STABLE kernel with a
page fault.
>How-To-Repeat:
Run ntpd long enough to get a valid /etc/ntp.drift file.
Run the following script.
#! /usr/bin/perl -w
$driftfile = "/etc/ntp.drift";
open(DF, $driftfile) || die "Can't open driftfile ($driftfile): $!\n";
while(<DF>) {
chop;
if (/^-?\d+\.\d+$/) {
$drift = $_;
} else {
die "Bogus value in driftfile $driftfile: <$_>\n";
}
}
close(DF);
print "drift is <$drift>\n";
$freq_adj = 1 - $drift / 1000000;
print "freq_adj is <$freq_adj>\n";
chop($i8254_freq = `sysctl -n machdep.i8254_freq`);
chop($tsc_freq = `sysctl -n machdep.tsc_freq 2> /dev/null`);
print "i8254_freq is <$i8254_freq>\n";
print "tsc_freq is <$tsc_freq>\n";
if ($i8254_freq > 1) {
$i8254_freq = int $i8254_freq * $freq_adj;
print "i8254_freq -> <$i8254_freq>\n";
print "i8254: ".`sysctl -w machdep.i8254_freq=$i8254_freq`;
}
if ($tsc_freq > 1) {
$tsc_freq = int $tsc_freq * $freq_adj;
print "tsc_freq -> <$tsc_freq>\n";
print "tsc: ".`sysctl -w machdep.tsc_freq=$tsc_freq`;
}
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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