Using these 4 points the ipm(4) driver calibrates the board with the projected screen. There are two possibilities to submit the coordinates to the ipm(4) driver.
On-The-Fly Calibration (non-permanen, w/o X restart)
If you don't specify any option ipmcali(1) will use the default on-the-fly configuration (default: /tmp/.ipm-calibration) and store the coordinates in this file. The driver will poll the calibration file on each pen stroke and adjust the calibration if the file is valid.This calibration method is non-permanent if you restart the X server it will be lost.
This calibration method doesn't require the X server to be restarted and will adjust the calibration on-the-fly.
XF86Config(5x) Calibration (permanent, w/ X restart)
The coordinates for the corners are printed as options for the ipm(4) driver. These options should be inserted into the ipm InputSection in the XF86Config(5x) file.This calibration method is permanent if you restart the X server it will read from the XF86Config(5x) file.
This calibration method does require the X server to be restarted before the calibration is active.
-c file
Write "on-the-fly" calibration to file. (default: /tmp/.ipm-calibration).
-w file
Write calibration for XF86Config to file.
-s
Write calibration for XF86Config to STDOUT.
-h
Print a help screen to STDERR.
-v
Verbose output, display desynced blocks.
device
A serial device, e.g. /dev/ttyS0. If "-" is used, ipmcali reads from STDIN.