regression: linux-image-2.6.32-20-generic doesn't boot on macbook 4.1

It just "hangs" during kernel initialization. Also either it doesn't switch to framebuffer or uses a framebuffer with less columns than -19 did.

I say it "hangs" because I can actually switch VTs but the boot doesn't continue.

Previous lucid kernels since beta1 up to and including linux-image-2.6.32-19-generic worked and
linux-image-2.6.32-19-generic still works on an update-as-of-today install.

As the macbook has no SysReq nor F13 keys I'm attaching a screenshot of VT1 after the boot hanged; the other VTs where blank.

During various attempts I also got a kernel trace (which however partly scrolls away before the kernel hangs) and, after a while some messages appeared on VT7; I'll attach screenshots for that later.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: linux-image-2.6.32-20-generic 2.6.32-20.29
Regression: Yes
Reproducible: Yes
ProcVersionSignature: Ubuntu 2.6.32-19.28-generic 2.6.32.10+drm33.1
Uname: Linux 2.6.32-19-generic i686
NonfreeKernelModules: wl
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: michele 1644 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0x90700000 irq 20'
   Mixer name : 'Realtek ALC889A'
   Components : 'HDA:10ec0885,106b3600,00100103'
   Controls : 35
   Simple ctrls : 22
Date: Mon Apr 12 09:50:15 2010
HibernationDevice: RESUME=UUID=0d182a1a-20c0-4b5a-a8ae-93688d66fee1
InstallationMedia: Error: [Errno 13] Permission denied: '/var/log/installer/media-info'
MachineType: Apple Inc. MacBook4,1
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-19-generic root=UUID=3f7919f6-a881-4335-ab54-c8e485e3afb4 ro quiet splash
ProcEnviron:
 LANGUAGE=en_IE:en_GB:en
 PATH=(custom, user)
 LANG=en_IE.utf8
 SHELL=/bin/bash
RelatedPackageVersions: linux-firmware 1.33
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
dmi.bios.date: 02/09/08
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MB41.88Z.00C1.B00.0802091535
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Mac-F22788A9
dmi.board.vendor: Apple Inc.
dmi.board.version: PVT
dmi.chassis.asset.tag: Asset Tag#
dmi.chassis.type: 2
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F22788A9
dmi.modalias: dmi:bvnAppleInc.:bvrMB41.88Z.00C1.B00.0802091535:bd02/09/08:svnAppleInc.:pnMacBook4,1:pvr1.0:rvnAppleInc.:rnMac-F22788A9:rvrPVT:cvnAppleInc.:ct2:cvrMac-F22788A9:
dmi.product.name: MacBook4,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.