Re: Detecting x86 LAPIC timer frequency from CPUID data

From: Thomas Gleixner
Date: Fri Apr 19 2019 - 16:52:08 EST


On Fri, 19 Apr 2019, Jacob Pan wrote:
> On Fri, 19 Apr 2019 10:57:10 +0200 (CEST)
> Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > On Fri, 19 Apr 2019, Daniel Drake wrote:
> > > 0x7FFFFF vs 0x7FFFFFFF, is that intentional?
> >
> > I don't think so. Looks like a failed copy and paste. Cc'ed Jacob, he
> > might know.
> >
> At the time of v2.6.35 both places use 0x7FFFFF. But later this patch
> increased the latter to 0x7FFFFFFF but forgot the first part. So I
> guess it is not exactly a failed copy and paste.
>
> commit 4aed89d6b515b9185351706ca95cd712c9d8d6a3
> Author: Pierre Tardy <pierre.tardy@xxxxxxxxx>
> Date: Thu Jan 6 16:23:29 2011 +0100
>
> x86, lapic-timer: Increase the max_delta to 31 bits

Indeed. Thanks for digging that up!

tglx