dumpreg < /dev/ttyN
This is useful for debugging or adding modes to a device driver. For example you can use Xfree86 to setup a given mode timing, then run dumpreg and use it's stdout to make your chipset driver use exactly this timing.
However, the recent change of svgalib to hunt an own free virtual console does not allow this, because it will make Xfree86 return to textmode first. You can avoid this by using the second form where N is the number of the virtual console on which Xfree86 runs (usually 7) as root.
This manual page was edited by Michael Weller <email@example.com>. The exact source of the referenced utility as well as of the original documentation is unknown.
It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>.
Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or corrections to this first version of the svgalib manual.