[REGRESSION][BISECTED][X86] next-20080526 hangs on boot

[Sitsofe Wheeler <sitsofe@yahoo.com>]

<posted & mailed>

When using a 32 bit linux-next-20080526 the bootup process will hang at a
random point (not even sysrq helps) with no additional output on the screen
(whereas linux-next-20080523 did boot). Mysteriously, booting with
nmi_watchdog=2 allows the boot to finish (booting with nmi_watchdog=1 still
stalls). I have bisected it down to commit
[d1b946b97d71423f365fa797d1428e1847c0bec1]:

commit d1b946b97d71423f365fa797d1428e1847c0bec1
Author: Cyrill Gorcunov <gorcunov@gmail.com>
Date:   Sat May 24 19:36:34 2008 +0400

    x86: nmi_32.c - add "panic" option

    Allow to pass "panic" option in 32bit mode

    Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
    Cc: hpa@zytor.com
    Cc: mingo@redhat.com
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Reverting this seemed to allow the boot to proceed without issue. Here is
the bisection log:

# bad: [5ffeee1785c30303007b3d2dce85402b0bbf9b00] Add linux-next specific
files
# good: [7b6c98f0853b86c101948f1bf4e0a21d3065944f] Add linux-next specific
files
git-bisect start 'next-20080526' 'next-20080523'
# bad: [cab464e32db5aef80c51831c20009ae7c3354396] Merge
commit 'x86/auto-x86-next'
git-bisect bad cab464e32db5aef80c51831c20009ae7c3354396
# good: [497d7294d4fb1a0d2ce14bb891a1d812b2af3745] Merge
branch 'x86/mpparse' into auto-x86-next
git-bisect good 497d7294d4fb1a0d2ce14bb891a1d812b2af3745
# good: [8315d6949d94b7513f8829b62d59d7d5699872dd] USB: driver for gotemp
device
git-bisect good 8315d6949d94b7513f8829b62d59d7d5699872dd
# good: [289c79a4bd350e8a25065102563ad1a183d1b402] vlan: Use bitmask of
feature flags instead of seperate feature bits
git-bisect good 289c79a4bd350e8a25065102563ad1a183d1b402
# bad: [c791e51837f26cba073d3c37cf04803bb3a5c6c0] Merge branch 'x86/timers'
into auto-x86-next
git-bisect bad c791e51837f26cba073d3c37cf04803bb3a5c6c0
# bad: [4039cbaacf7874ab1effd0e9fb6c60bf9217f373] Merge branch 'x86/nmi'
into auto-x86-next
git-bisect bad 4039cbaacf7874ab1effd0e9fb6c60bf9217f373
# bad: [4b82b277707a39b97271439c475f186f63ec4692] x86: nmi_32.c - add
nmi_watchdog_default helper
git-bisect bad 4b82b277707a39b97271439c475f186f63ec4692
# good: [e56b3a12c45e439169f2d1f7194be397667320a6] x86: nmi - die_nmi()
output message unification
git-bisect good e56b3a12c45e439169f2d1f7194be397667320a6
# bad: [d1b946b97d71423f365fa797d1428e1847c0bec1] x86: nmi_32.c -
add "panic" option
git-bisect bad d1b946b97d71423f365fa797d1428e1847c0bec1
# good: [c6425b9f143a75bbcd0a7684b4df40e20d0b2f32] x86: move do_nmi(),
stop_nmi() and restart_nmi() to traps_64.c
git-bisect good c6425b9f143a75bbcd0a7684b4df40e20d0b2f32

-- 
Sitsofe | http://sucs.org/~sits/