On 13/03/2020 09:26, Jan Beulich wrote: > --- a/xen/arch/x86/apic.c > +++ b/xen/arch/x86/apic.c > @@ -1249,17 +1249,16 @@ static int __init calibrate_APIC_clock(v > tt2 = apic_read(APIC_TMCCT); > t2 = rdtsc_ordered(); > > - result = (tt1-tt2)*APIC_DIVISOR/LOOPS; > + bus_freq = (tt1 - tt2) * APIC_DIVISOR * LOOPS_FRAC; > > - apic_printk(APIC_VERBOSE, "..... CPU clock speed is %ld.%04ld MHz.\n", > - ((long)(t2 - t1) / LOOPS) / (1000000 / HZ), > - ((long)(t2 - t1) / LOOPS) % (1000000 / HZ)); > + apic_printk(APIC_VERBOSE, "..... CPU clock speed is %lu.%04lu MHz.\n", > + ((unsigned long)(t2 - t1) * LOOPS_FRAC) / 1000000, > + ((unsigned long)(t2 - t1) * LOOPS_FRAC / 100) % 10000);
If I'm not mistaken, this expression only works because of the L->R associativity (given the same precedence of * and /) grouping it as ((t2-t1) * 10) / 100 as opposed to (t2-t1) * (10 / 100), where the latter would truncate to 0. I think some extra brackets would help for clarity. That said, what is wrong with keeping the original form? I realise this is only for a printk(), but the div instruction can't be shared between the two halves. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
