Re: 2.6.14-rc4-rt1 - enable IRQ-off tracing causes kernel to fault at boot
From: Mark Knecht
Date: Fri Oct 14 2005 - 14:41:33 EST
On 10/14/05, Mark Knecht <markknecht@xxxxxxxxx> wrote:
> On 10/13/05, Ingo Molnar <mingo@xxxxxxx> wrote:
> > * Mark Knecht <markknecht@xxxxxxxxx> wrote:
> > > Ingo & Steve,
> > > Thank you for your great instructions that even a guitar player
> > > could basically follow. After about an hour of messing around I did
> > > manage to capture the crash. The console file is attached.
> > >
> > > NOTE: The first time I booted the kernel it got to the crash point and
> > > the machine rebooted. The second time it booted I got the trace. Both
> > > boots are in the capture file.
> > thanks, this log is much more informative. No smoking gun though, but it
> > seems something fundamental (probably lowlevel x64 code) has been broken
> > by -rt1.
> > Do the crashes go away if you take the -rc3-rt13 version of
> > arch/x86_64/kernel/entry.S and copy it over into the -rc4-rt1 tree?
> > [this undoes a particular set of CONFIG_CRITICAL_IRQSOFF_TIMING fixes
> > from the x64 code, which i did during -rc3-rt13 => -rc4-rt1]
> Indeed it is fixed by doing this. Options are on but the modified
> kernel does boot:
Good news and strange news:
GOOD NEWS: This problem may or may not be fixed in 2.6.14-rc4-rt5. The
kernel now boots for me with IRQoff tracing enabled, but once again
I'm seeing times that appear to be the timer frequency:
( softirq-timer/0-3 |#0): new 998 us maximum-latency critical section.
=> started at timestamp 403325647: <acpi_processor_idle+0x20/0x379>
=> ended at timestamp 403326645: <thread_return+0xb5/0x11a>
| preempt count: 00000001 ]
| 1-level deep critical section nesting:
.. [<ffffffff803ed5b8>] .... __schedule+0xb8/0x5a6
.....[<00000000>] .. ( <= _stext+0x7feff0e8/0xe8)
=> dump-end timestamp 403326728
lightning ~ #
STRANGE NEWS: It now takes between 1-2 minutes for Gnome to log out.
I think possibly something is not exactly right about the timers yet.
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