Apply by doing:
cd /usr/src
patch -p0 < 012_imacdv.patch
And then rebuild your kernel.
Index: sys/arch/powerpc/pci/vgafb_pci.c
===================================================================
RCS file: /cvs/src/sys/arch/powerpc/pci/vgafb_pci.c,v
retrieving revision 1.1
diff -u -r1.1 vgafb_pci.c
--- sys/arch/powerpc/pci/vgafb_pci.c 2000/09/06 02:12:15 1.1
+++ sys/arch/powerpc/pci/vgafb_pci.c 2000/12/15 01:22:32
@@ -1,4 +1,4 @@
-/* $OpenBSD: vgafb_pci.c,v 1.1 2000/09/06 02:12:15 rahnds Exp $ */
+/* $OpenBSD: vgafb_pci.c,v 1.2 2000/11/21 02:03:44 deraadt Exp $ */
/* $NetBSD: vga_pci.c,v 1.4 1996/12/05 01:39:38 cgd Exp $ */
/*
@@ -231,6 +231,9 @@
potential = 1;
if (PCI_CLASS(pa->pa_class) == PCI_CLASS_DISPLAY &&
PCI_SUBCLASS(pa->pa_class) == PCI_SUBCLASS_DISPLAY_VGA)
+ potential = 1;
+ if (PCI_CLASS(pa->pa_class) == PCI_CLASS_DISPLAY &&
+ PCI_SUBCLASS(pa->pa_class) == PCI_SUBCLASS_DISPLAY_MISC)
potential = 1;
if (!potential)
Index: sys/arch/powerpc/pci/vgafb_pcivar.h
===================================================================
RCS file: /cvs/src/sys/arch/powerpc/pci/vgafb_pcivar.h,v
retrieving revision 1.1
diff -u -r1.1 vgafb_pcivar.h
--- sys/arch/powerpc/pci/vgafb_pcivar.h 2000/09/06 02:12:15 1.1
+++ sys/arch/powerpc/pci/vgafb_pcivar.h 2000/12/15 01:22:32
@@ -1,4 +1,4 @@
-/* $OpenBSD: vgafb_pcivar.h,v 1.1 2000/09/06 02:12:15 rahnds Exp $ */
+/* $OpenBSD: vgafb_pcivar.h,v 1.2 2000/11/21 02:03:45 deraadt Exp $ */
/* $NetBSD: vga_pcivar.h,v 1.1 1996/11/19 04:38:36 cgd Exp $ */
/*
@@ -31,6 +31,8 @@
#define DEVICE_IS_VGA_PCI(class, id) \
(((PCI_CLASS(class) == PCI_CLASS_DISPLAY && \
PCI_SUBCLASS(class) == PCI_SUBCLASS_DISPLAY_VGA) || \
+ (((PCI_CLASS(class) == PCI_CLASS_DISPLAY && \
+ PCI_SUBCLASS(class) == PCI_SUBCLASS_DISPLAY_MISC) || \
(PCI_CLASS(class) == PCI_CLASS_PREHISTORIC && \
PCI_SUBCLASS(class) == PCI_SUBCLASS_PREHISTORIC_VGA)) ? 1 : 0)
