Re: 2.6.12 hangs on boot

From: Alexander Y. Fomichev <gluk@php4.ru>
Date: Jul 18, 2005, 11:27 UTC
Message-ID: <200507181527.16652.gluk@php4.ru>
In-Reply-To: <Pine.LNX.4.58.0506241446440.11175@ppc970.osdl.org>

On Saturday 25 June 2005 02:20, Linus Torvalds wrote:

Show 11 quoted lines

> On Wed, 22 Jun 2005, Alexander Y. Fomichev wrote:
> > I've been trying to switch from 2.6.12-rc3 to 2.6.12 on Dual EM64T 2.8
> > GHz [ MoBo: Intel E7520, intel 82801 ]
> > but kernel hangs on boot right after records:
> >
> > Booting processor 2/1 rip 6000 rsp ffff8100023dbf58
> > Initializing CPU#2
>
> Hmm.. Since you seem to be a git user, maybe you could try the git
> "bisect" thing to help narrow down exactly where this happened (and help
> test that thing too ;).

[skiped]

Ok, as i can see [and as Andi guessed http://bugme.osdl.org/show_bug.cgi?id=4792] issue have been introduced by new TSC sync algorithm git id: dda50e716dc9451f40eebfb2902c260e4f62cf34.

And, yes, seems like it depends of timings... In my case kludge with insertion of low delay (e.g. printk) between cpu_set/mb and tsc_sync_wait() makes kernel bootable.

diff -urN b/arch/x86_64/kernel/smpboot.c a/arch/x86_64/kernel/smpboot.c --- b/arch/x86_64/kernel/smpboot.c 2005-07-17 21:55:55.000000000 +0400 +++ a/arch/x86_64/kernel/smpboot.c 2005-07-17 21:57:56.000000000 +0400

@@ -451,6 +451,7 @@
 	cpu_set(smp_processor_id(), cpu_online_map);
 	mb();
 
+	printk(KERN_INFO "We're still here!\n");
 	/* Wait for TSC sync to not schedule things before.
 	   We still process interrupts, which could see an inconsistent
 	   time in that window unfortunately. */

-- 
Best regards.
        Alexander Y. Fomichev <gluk@php4.ru>
        Public PGP key: http://sysadminday.org.ru/gluk.asc