diff options
| -rw-r--r-- | sys/src/9/pc/i8253.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/sys/src/9/pc/i8253.c b/sys/src/9/pc/i8253.c index 2e3ea2162..04af79edb 100644 --- a/sys/src/9/pc/i8253.c +++ b/sys/src/9/pc/i8253.c @@ -165,7 +165,7 @@ guesscpuhz(int aalcycles) cpufreq = (vlong)loops*((aalcycles*2*Freq)/x); m->loopconst = (cpufreq/1000)/aalcycles; /* AAM+LOOP's for 1 ms */ - if(m->havetsc){ + if(m->havetsc && a != b){ /* a == b means virtualbox has confused us */ /* counter goes up by 2*Freq */ b = (b-a)<<1; b *= Freq; @@ -185,6 +185,9 @@ guesscpuhz(int aalcycles) m->cpuhz = cpufreq; } + /* don't divide by zero in trap.c */ + if(m->cpumhz == 0) + panic("guesscpuhz: zero m->cpumhz"); i8253.hz = Freq<<Tickshift; } |