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Subject: Re: Linux-2.6.21-rc3 : Dynticks and High resolution Timer hanging
	the system
From: Thomas Gleixner <tglx@linutronix.de>
Reply-To: tglx@linutronix.de
To: Stephane Casset <sept@logidee.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Ingo Molnar <mingo@elte.hu>
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Date: Wed, 07 Mar 2007 20:52:10 +0100
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On Wed, 2007-03-07 at 20:12 +0100, Stephane Casset wrote:
> I also tried compiling the kernel without Tickless and without  High
> resolution timer, this kernel is working ok and is one of the first
> kernel to suspend and resume from RAM. Congratulations ! ;p
>
> I tried to compile te kernel with only Tickless System or  High
> Resolution timer, both hang on boot.

There should be no difference between compile time and runtime
disabling.

> The hang is just after :
> ACPI: PCI Interrupt 0000:00:1f.1[A] -> GSI 18 (level, low) -> IRQ 18
> ICH5: chipset revision 2
> ICH5: not 100% native mode: will probe irqs later
>     ide0: BM-DMA at 0x2040-0x2047, BIOS settings: hda:DMA, hdb:pio
>     ide1: BM-DMA at 0x2048-0x204f, BIOS settings: hdc:DMA, hdd:pio
> 
> And I have the message :
> Switched to NOHZ mode on CPU #1
> or
> Switched to high resolution mode on CPU #1
> Depending on the option enabled/disabled 
> 
> What can I do to help find the bug ?

Can you capture a boot log with highres and/or dynticks enabled ? 

Enable CONFIG_SERIAL_8250_CONSOLE and add "console=ttyS0,115200" to the
commandline. Capture the output with minicom on a second box.

Also please enable CONFIG_MAGIC_SYSRQ and try to send a SysRq-T and a
SysRq-Q to the machine via keyboard or the serial line.

Thanks

	tglx