The Linux keyboard and console HOWTO: Changing the video mode

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## 16. Changing the video mode

As far as I know there are 6 ways to change resolution:

1. At compile time: change the line

> `

>             SVGA_MODE=      -DSVGA_MODE=NORMAL_VGA

> `

in `/usr/src/linux/Makefile`.

1A. After compilation: use `rdev -v` - a terrible hack, but it exists.

2. At boot time: put `vga=ask` in the lilo config file, and lilo will ask you what video mode you want. Once you know, put `vga=`mypreference.

3. At run time: A. Use the `resizecons` command. (This is a very primitive wrapper around the VT_RESIZE ioctl.) B. Use the `SVGATextMode` command. (This is a less primitive wrapper around the VT_RESIZE ioctl.)

4. Not "on the console": Under `dosemu`, or with svgalib etc. you can change the hardware video mode without the console driver being aware of it. Sometimes this is useful in getting `resizecons` or `SVGATextMode` set up: use `dosemu` and some DOS program to get into the desired videomode, dump (say from another VT) the contents of all video hardware registers, and use that in the initialization that `resizecons` and `SVGATextMode` require. In some cases where the video mode has gotten into some unusable state, starting `dosemu`, relying on the BIOS to set up the video mode, and then killing `dosemu` (with `kill -9`), is the easiest way to get into shape again.

## 16.1 Instructions for the use of resizecons

Get svgalib and compile the program `restoretextmode`. Boot up your machine in all possible video modes (using `vga=ask` in the lilo config file), and write the video hardware register contents to files CxR (C=cols, R=rows), e.g., 80x25, 132x44, etc. Put these files in `/usr/lib/kbd/videomodes`. Now `resizecons 132x44` will change videomode for you (and send SIGWINCH to all processes that need to know about this, and load another font if necessary).

At present, `resizecons` only succeeds when there is memory enough for both the old and the new consoles at the same time.

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