Re: [Qemu-devel] [PATCH 3/4] Add support for HPET periodic timer.

Dan Kenigsberg
2007-08-22T06:48:51Z

On Tue, Aug 21, 2007 at 01:15:22PM -0700, Matthew Kent wrote:
> On Tue, 2007-21-08 at 21:40 +0200, Luca wrote:
> > On 8/21/07, Matthew Kent <mkent-rTVjrLRGJfNWk0Htik3J/w@public.gmane.org> wrote:
> > > On Sat, 2007-18-08 at 01:11 +0200, Luca Tettamanti wrote:
> > > > plain text document attachment (clock-hpet)
> > > > Linux operates the HPET timer in legacy replacement mode, which means that
> > > > the periodic interrupt of the CMOS RTC is not delivered (qemu won't be able
> > > > to use /dev/rtc). Add support for HPET (/dev/hpet) as a replacement for the
> > > > RTC; the periodic interrupt is delivered via SIGIO and is handled in the
> > > > same way as the RTC timer.
> > > >
> > > > Signed-off-by: Luca Tettamanti <kronos.it-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > >
> > > I must be missing something silly here.. should I be able to open more
> > > than one instance of qemu with -clock hpet? Because upon invoking a
> > > second instance of qemu HPET_IE_ON fails.
> >
> > It depends on your hardware. Theoretically it's possible, but I've yet
> > to see a motherboard with more than one periodic timer.
>
> Ah thank you, after re-reading the docs I think I better understand
> this.

In a risk of being off-topic, maybe you can help me try the hpet support.
When I try the hpet Documentation demo I get

# ./hpet poll /dev/hpet 1 1000
-hpet: executing poll
hpet_poll: info.hi_flags 0x0
hpet_poll, HPET_IE_ON failed

while I have

$ dmesg|grep -i HPET
ACPI: HPET 7D5B6AE0, 0038 (r1 A M I OEMHPET 5000708 MSFT 97)
ACPI: HPET id: 0x8086a301 base: 0xfed00000
hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0, 0
hpet0: 4 64-bit timers, 14318180 Hz
hpet_resources: 0xfed00000 is busy
Time: hpet clocksource has been installed.

Any idea what I am misconfiguring?

Thanks,

Dan.