Re: port-amd64/38478 (panic on boot when attaching cpu17)

[Andrew Doran <ad%NetBSD.org@localhost>]

The following reply was made to PR port-amd64/38478; it has been noted by GNATS.

From: Andrew Doran <ad%NetBSD.org@localhost>
To: Christoph Egger <Christoph_Egger%gmx.de@localhost>
Cc: gnats-bugs%NetBSD.org@localhost
Subject: Re: port-amd64/38478 (panic on boot when attaching cpu17)
Date: Tue, 13 May 2008 14:59:12 +0100

 On Tue, May 13, 2008 at 03:45:42PM +0200, Christoph Egger wrote:
 > 
 > > Synopsis: panic on boot when attaching cpu17
 > > 
 > > State-Changed-From-To: open->feedback
 > > State-Changed-By: ad%NetBSD.org@localhost
 > > State-Changed-When: Sun, 11 May 2008 22:57:34 +0000
 > > State-Changed-Why:
 > > Can you confirm that this is fixed in -current?
 > 
 > Yes, partially at least.
 > There's still a panic on boot related to many cpus:
 > 
 > kernel double fault trap, code=0
 > Stopped in pid 0.12 (system) at netbsd:Xintr_lapic_ltimer+0x38: movq   
 > %rdi,0(%rsp)
 > 
 > %rsp value is 0xffff80004677afd0
 > 
 > The double fault comes from a stack corruption/overflow.
 > The interrupt stack is filled up with so many lapic timer handler's running 
 > concurrently.
 
 A backtrace shows them recursing? What other functions+offsets are involved
 in the recursion? At what point in the boot process does it occur? Can you
 pick a couple of other CPUs and see what they are doing?
  
 > I suggest to make the interrupt stack per-cpu.
 
 CPUs never share a stack.
 
 Thanks,
 Andrew