Video Questions

How do I choose what video mode to use with Linux?

This is done with the "video" boot parameter. For details on what resolutions are supported, you'll want to read Documentation/m68k/framebuffer.txt (in 2.1/2.2, Documentation/fb/framebuffer.txt) and Documentation/m68k/kernel-options.txt in the Linux/m68k kernel source tree (the former document only appeared in 2.0.28).

You can also specify what font you want to use with the font option to 'video'.

For example, to boot into 640x480x4 mode on an Amiga with a 31 kHz or multiscan monitor, use video=vga.

I use video=font:PEARL8x8,vga on my Amiga 4000, for a very nice 80x60 text display.

When I run X, it complains about invalid modes

The easiest way to fix this is to change an uncommented "Modes" line in your /etc/XF86Config to read:

Modes "default"

Later on, you can get Geert Uytterhoeven's fbset program (from or the Debian distribution) and customize your video modes.

If you have an old XF86Config laying around, you may want to copy the example provided at /usr/X11R6/lib/X11/ (in Debian 2.1, /usr/doc/xserver-common/examples/ into /etc/XF86Config and then edit the new configuration file.

I've got fbset, but I can't create any video modes

(written by Geert Uytterhoeven)

If you have a PAL-based Amiga with a true Multisync monitor (like the A1960), try these as starters (they should be typed on one line; they are split up to make the FAQ format correctly):

ModeLine "vga70" 28.376 640 736 848 912 400 412 414 449 +VSync +CSync

ModeLine "vga" 28.376 640 736 848 912 480 489 491 521

ModeLine "832x624" 28.376 832 940 1020 1024 624 628 630 660 Interlace \
+HSync +VSync

ModeLine "832x600" 28.376 832 964 1044 1096 600 600 602 636 Interlace \
+HSync -VSync

ModeLine "896x672" 28.376 896 1044 1108 1160 672 676 678 708 \
Interlace -HSync +VSync -CSync

ModeLine "960x720" 28.376 960 1132 1172 1224 720 720 722 754 \
Interlace -HSync -VSync -CSync

ModeLine "1024x768" 28.376 1024 1196 1212 1288 768 772 774 804 \
Interlace -HSync +VSync -CSync

For NTSC, you can try replacing 28.376 on each modeline with 28.636 (but this hasn't been tested). Note that each ModeLine should be entered on one line in your XF86Config file.

You may also have some files (as /etc/fb.modes.*) that have some preconfigured video modes.

How do I create the framebuffer device nodes?

(written by Geert Uytterhoeven)

You can create the frame buffer special device nodes for the Amiga using the following commands:

mknod /dev/fb0 c 29 0
mknod /dev/fb0current c 29 0
mknod /dev/fb0autodetect c 29 1
mknod /dev/fb0ntsc c 29 2
mknod /dev/fb0ntsc-lace c 29 3
mknod /dev/fb0pal c 29 4
mknod /dev/fb0pal-lace c 29 5
mknod /dev/fb0multiscan c 29 6
mknod /dev/fb0multiscan-lace c 29 7
mknod /dev/fb0a2024-10 c 29 8
mknod /dev/fb0a2024-15 c 29 9
mknod /dev/fb0euro36 c 29 0
mknod /dev/fb0euro36-lace c 29 11
mknod /dev/fb0euro72 c 29 12
mknod /dev/fb0euro72-lace c 29 13
mknod /dev/fb0super72 c 29 14
mknod /dev/fb0super72-lace c 29 15
mknod /dev/fb0dblntsc c 29 16
mknod /dev/fb0dblntsc-ff c 29 17
mknod /dev/fb0dblntsc-lace c 29 18
mknod /dev/fb0dblpal c 29 19
mknod /dev/fb0dblpal-ff c 29 20
mknod /dev/fb0dblpal-lace c 29 21
mknod /dev/fb0vga c 29 22
mknod /dev/fb0vga70 c 29 23
mknod /dev/fb0user0 c 29 24
mknod /dev/fb0user1 c 29 25
mknod /dev/fb0user2 c 29 26
mknod /dev/fb0user3 c 29 27
mknod /dev/fb0user4 c 29 28
mknod /dev/fb0user5 c 29 29
mknod /dev/fb0user6 c 29 30
mknod /dev/fb0user7 c 29 31

However, these should be pre-created when you install your distribution.

How do I make sure that I do not damage my monitor when running X?

(written by Haidinger Walter)

Before trying to run X, you should edit /etc/XF86Config. Look for the Monitor section. Set the "HorizSync" and "VertRefresh" values to the specifications matching your monitor (which should be listed in your monitor's manual).

For example, if you have an M1438S monitor:

HorizSync   15-40
VertRefresh 45-90

My MAG 510V2 SVGA monitor has the following settings:

HorizSync   30-54
VertRefresh 50-100

Of course, this provides neither a warranty nor an insurance that you cannot damage your monitor, but it will be much more difficult now...

Do a "man XF86Config" for a detailed description of these options.

(Maintainer's note: I fried an A1960 monitor once by blindly copying someone's HorizSync and VertRefresh values from an XF86Config file. Make certain that you are using the correct values for YOUR monitor; they should be in the book that came with it. And if your monitor starts acting funny, switch it off immediately!: if I had switched mine off, I could have saved myself a $100 US repair bill.)