linux-kernel - Re: HPET timer broken using 2.6.23.13 / nanosleep() hangs

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Message-Id: <200801141942.41732.balajirrao@gmail.com>
Date:	Mon, 14 Jan 2008 19:42:41 +0530
From:	Balaji Rao <balajirrao@...il.com>
To:	Clemens Ladisch <clemens@...isch.de>
Cc:	Andrew Paprocki <andrew@...iboo.com>, linux-kernel@...r.kernel.org
Subject: Re: HPET timer broken using 2.6.23.13 / nanosleep() hangs

On Monday 14 January 2008 06:29:27 pm Clemens Ladisch wrote:
> Andrew Paprocki wrote:
> > I started debugging a problem I was having with my sky2 network driver
> > under 2.6.23.13. The investigation led me to find that the HPET timer
> > wasn't working at all, causing the sky2 driver to not work properly.
> > Simple example:
> >
> > am2:/sys/devices/system/clocksource/clocksource0# echo hpet >
> > current_clocksource am2:/sys/devices/system/clocksource/clocksource0#
> > time sleep 1
> > <hangs indefinetly...>
> >
> > Running strace shows it blocked on nanosleep(). I'm building the
> > kernel with the processor type set to Athalon64. I've built it with
> > and without SMP and high-res timers enabled and I get the same result.
> > My previous 2.6.18-4 kernel works because it does not install HPET as
> > the default timer. The same behavior occurs in 2.6.24-rc7 git head.
> > I've attached the config/dmesg below.
> >
> > Under 2.6.18-4 (Debian stock kernel):
> >
> > ACPI: HPET id: 0x10b9a201 base: 0xfed00000
> > hpet0: at MMIO 0xfed00000 (virtual 0xf8800000), IRQs 2, 8, 0, 0
> > hpet0: 4 32-bit timers, 14318180 Hz
> > Using HPET for base-timer
> > hpet_resources: 0xfed00000 is busy
> > Time: tsc clocksource has been installed.
> >
> > Under 2.6.23.13 w/ SMP:
> >
> > ACPI: HPET 37FE7400, 0038 (r1 RS690  AWRDACPI 42302E31 AWRD       98)
> > ACPI: HPET id: 0x10b9a201 base: 0xfed00000
> > Time: tsc clocksource has been installed.
> > Clocksource tsc unstable (delta = 500013666 ns)
> > Time: hpet clocksource has been installed.
>
> The lines prefixed with "hpet0:" are missing; apparently, hpet_alloc()
> was never called because hpet_reserve_platform_timers() is disabled
> because CONFIG_HPET is not set.  Try enabling this option.  (CONFIG_HPET
> is in the "Character Devices" kernel config menu.)
>
> That this option would be required to get the platform HPET code to work
> seems like a bug.
>
This doesn't seem to be the issue, as I have not been able to reproduce the bug on my Core 2 system with the same config.
HPET clocksource works fine with only CONFIG_HPET_TIMER.
>
> Regards,
> Clemens
> --
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