A few lines from linux-2.2.10/Documentation/m68k/kernel-options.txt in case
you have to edit your Start script (ie, you have an AGA capable machine, but
want to use a pal display, use video=amifb:pal. See below for more.).

5) Options for Amiga Only:
==========================

5.1) video=
-----------

Syntax: video=<fbname>:<sub-options...>

The <fbname> parameter specifies the name of the frame buffer, valid
options are `amifb', `cyber', `virge', `retz3' and `clgen', provided
that the respective frame buffer devices have been compiled into the
kernel (or compiled as loadable modules). The behavior of the <fbname>
option was changed in 2.1.57 so it is now recommended to specify this
option.

The <sub-options> is a comma-separated list of the sub-options listed
below. This option is organized similar to the Atari version of the
"video"-option (4.1), but knows fewer sub-options.

5.1.1) video mode
-----------------

Again, similar to the video mode for the Atari (see 4.1.1). Predefined
modes depend on the used frame buffer device.

OCS, ECS and AGA machines all use the color frame buffer. The following
predefined video modes are available:

NTSC modes:
 - ntsc            : 640x200, 15 kHz, 60 Hz
 - ntsc-lace       : 640x400, 15 kHz, 60 Hz interlaced
PAL modes:
 - pal             : 640x256, 15 kHz, 50 Hz
 - pal-lace        : 640x512, 15 kHz, 50 Hz interlaced
ECS modes:
 - multiscan       : 640x480, 29 kHz, 57 Hz
 - multiscan-lace  : 640x960, 29 kHz, 57 Hz interlaced
 - euro36          : 640x200, 15 kHz, 72 Hz
 - euro36-lace     : 640x400, 15 kHz, 72 Hz interlaced
 - euro72          : 640x400, 29 kHz, 68 Hz
 - euro72-lace     : 640x800, 29 kHz, 68 Hz interlaced
 - super72         : 800x300, 23 kHz, 70 Hz
 - super72-lace    : 800x600, 23 kHz, 70 Hz interlaced
 - dblntsc-ff      : 640x400, 27 kHz, 57 Hz
 - dblntsc-lace    : 640x800, 27 kHz, 57 Hz interlaced
 - dblpal-ff       : 640x512, 27 kHz, 47 Hz
 - dblpal-lace     : 640x1024, 27 kHz, 47 Hz interlaced
 - dblntsc         : 640x200, 27 kHz, 57 Hz doublescan
 - dblpal          : 640x256, 27 kHz, 47 Hz doublescan
VGA modes:
 - vga             : 640x480, 31 kHz, 60 Hz
 - vga70           : 640x400, 31 kHz, 70 Hz

Please notice that the ECS and VGA modes require either an ECS or AGA
chipset, and that these modes are limited to 2-bit color for the ECS
chipset and 8-bit color for the AGA chipset.

5.1.2) depth
------------

Syntax: depth:<nr. of bit-planes>

Specify the number of bit-planes for the selected video-mode.

5.1.3) inverse
--------------

Use inverted display (black on white). Functionally the same as the
"inverse" sub-option for the Atari.

5.1.4) font
-----------

Syntax: font:<fontname>

Specify the font to use in text modes. Functionally the same as the
"font" sub-option for the Atari, except that `PEARL8x8' is used instead
of `VGA8x8' if the vertical size of the display is less than 400 pixel
rows.

5.1.5) monitorcap:
-------------------

Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>

This describes the capabilities of a multisync monitor. For now, only
the color frame buffer uses the settings of "monitorcap:".

  <vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
your monitor can work with, in Hz. <hmin> and <hmax> are the same for
the horizontal frequency, in kHz.

  The defaults are 50;90;15;38 (Generic Amiga multisync monitor).