Ted Unangst [[email protected]] wrote:
> On Thu, Sep 13, 2012 at 15:46, Chris Cappuccio wrote:
> > Mark Kettenis [[email protected]] wrote:
> >> > Date: Wed, 15 Aug 2012 11:02:43 -0400
> >> > From: Ted Unangst <[email protected]>
> >> >
> >> > The acpihpet timer is, in my testing, lots better than the acpitimer.
> >> > Faster to read and more precise. They should not have the same quality
> >> > value. Double acpihpet.
> >>
> >> Since both acpitimer(4) and acpihpet(4) are based on an abstract
> >> specification that AFAIK doesn't say anything about the actual
> >> underlying hardware I'm totally unconvinced unless you can show this
> >> to be true on a wide variety of hardware.
> >>
> >
> > HPET on some processors is emulated in software via BIOS. Ring -1 or
> > whatever. I believe one of either the AMD Elan SC420 or the AMD Geode LX
> > fits in this category.
>
> hpet or just regular acpi timer?
I'm not sure why I thought it was those two.
Must be this that i'm thinking of from acpihpet.c but it's for a newer chip
that provides an HPET (sometimes).
/*
* Revisions 0x30 through 0x3a of the AMD SB700, with spread
* spectrum enabled, have an SMM based HPET emulation that's
* subtly broken. The hardware is initialized upon first
* access of the configuration register. Initialization takes
* some time during which the configuration register returns
* 0xffffffff.
*/
