Re: Long timeout when booting >= 2.6.38

[Christian Hoffmann]

On 05/05/2011 10:25 AM, Thomas Gleixner wrote:
> On Wed, 4 May 2011, john stultz wrote:
>
> > On Wed, 2011-05-04 at 09:31 +0200, Christian Hoffmann wrote:
> > > In fact, switching to acpi_pm doesn't seem to work:
> > >
> > > $ dmesg | grep clock
> > >
> > > [    0.000000] Command line: BOOT_IMAGE=/vmlinuz-2.6.39-rc5-ch-broken+
> > > root=/dev/mapper/vg-root ro quiet splash vt.handoff=7 clocksource=acpi_pm
> > > [    0.000000] Kernel command line:
> > > BOOT_IMAGE=/vmlinuz-2.6.39-rc5-ch-broken+ root=/dev/mapper/vg-root ro
> > > quiet splash vt.handoff=7 clocksource=acpi_pm
> > > [    0.000000] hpet clockevent registered
> > > [    1.413835] Switching to clocksource hpet
> > > [    1.420762] Override clocksource acpi_pm is not HRT compatible.
> > > Cannot switch while in HRT/NOHZ mode
> > > [  147.940143] Refined TSC clocksource calibration: 2809.409 MHz.
> > > [  147.940147] Switching to clocksource tsc
> >
> > So I think I've sorted this out.
> >
> > The watchdog code is what enables CLOCK_SOURCE_VALID_FOR_HRES, but we
> > actually end up selecting the clocksource before we enqueue it into the
> > watchdog list, so that's why we see the warning.
> >
> > I suspect the following will resolve this detail.
>
> It does. Good catch!
>
> > Signed-off-by: John Stultz<johnstul@xxxxxxxxxx>
> >
> > diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
> > index 6519cf6..0e17c10 100644
> > --- a/kernel/time/clocksource.c
> > +++ b/kernel/time/clocksource.c
> > @@ -685,8 +685,8 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
> >   	/* Add clocksource to the clcoksource list */
> >   	mutex_lock(&clocksource_mutex);
> >   	clocksource_enqueue(cs);
> > -	clocksource_select();
> >   	clocksource_enqueue_watchdog(cs);
> > +	clocksource_select();
> >   	mutex_unlock(&clocksource_mutex);
> >   	return 0;
> >   }
> > @@ -706,8 +706,8 @@ int clocksource_register(struct clocksource *cs)
> >
> >   	mutex_lock(&clocksource_mutex);
> >   	clocksource_enqueue(cs);
> > -	clocksource_select();
> >   	clocksource_enqueue_watchdog(cs);
> > +	clocksource_select();
> >   	mutex_unlock(&clocksource_mutex);
> >   	return 0;
> >   }

I can now select clocksource=acpi_pm as kernel parameter. The boot still 
hangs after "MSI quirk detected...", but the timestamps in dmesg don't 
show the jump anymore.

[    1.426107] NET: Registered protocol family 1
[    1.426162] pci 0000:00:01.0: MSI quirk detected; subordinate MSI 
disabled
[    2.300212] pci 0000:01:05.0: Boot video device
[    2.300226] PCI: CLS 64 bytes, default 64


Full dmesg is here:
http://pastebin.com/raw.php?i=3Fctvsrp

Rgds,
Chris

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