linux-kernel - Re: [PATCH 8/8] x86: I/O APIC: Timer through 8259A second-chance

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Message-ID: <20080605190045.GD7030@cvg>
Date:	Thu, 5 Jun 2008 23:00:45 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	the arch/x86 maintainers <x86@...nel.org>
Subject: Re: [PATCH 8/8] x86: I/O APIC: Timer through 8259A second-chance

[Maciej W. Rozycki - Thu, Jun 05, 2008 at 07:33:04PM +0100]
| On Thu, 5 Jun 2008, Ingo Molnar wrote:
| 
| > NOTE: you need to copy out and use the boot parameters from the boot 
| > log:
| > 
| >  [ 0.000000] Command line: root=/dev/sda6 console=ttyS0,115200 
| >  earlyprintk=se rial,ttyS0,115200 debug initcall_debug apic=verbose 
| >  sysrq_always_enabled ignore _loglevel selinux=0 nmi_watchdog=1 
| >  profile=0 maxcpus=1 nosmp no_hz=off highres =0 noapic nolapic_timer 
| >  hpet=disable idle=mwait
| > 
| > as -tip testing occasionally randomizes boot parameters too. (to find 
| > regressions like this) Let me know if you cannot reproduce this.
| 
|  Thanks.  I figured out I cannot build an x86-64 kernel, because my i386
| compiler does not support the target.  Probably because of target library
| dependencies at the time I built my compiler.  I would have to build a
| bare-iron cross-compiler for the x86-64 which I'd rather not to just to
| fix this small problem -- it usually takes a few days to sort out all the
| pesky details when doing such a build from scratch, so it better be well
| justified.
| 
|  However, the reason is quite clear to me -- the command line specifies
| "noapic" among others (there is also "nosmp", but probably overridden by
| "maxcpus=1" -- I am afraid there is no clear precedence among these
| options), so the bug is the I/O APIC NMI watchdog is tried at all.  This
| is also clearly seen from the log where the I/O APIC is not set up at all.  
| 
|  A fix along the lines of what I implemented for "nosmp" in the
| "nosmp-watchdog" patch is needed which I will post shortly.  It's needed
| both for the i386 and the x86-64 target; hopefully the latter does not
| differ too much from the former.
| 
|   Maciej
| 

Btw, just for the record: my hang was exactly on same line as Ingo reported:

static int __init pci_acpi_init(void) {
...
	printk(KERN_INFO "PCI: Using ACPI for IRQ routing\n");
...
}

well, Ingo had a few additional messages caused by debug_initcall,
but I guess there was a real hang. I mean acpi_irq_penalty_init()
is never reached (I've added a few printk there to be sure).

		- Cyrill -
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