Dump Video BIOS at FreeBSD - how to do it?

While trying to dump Video BIOS of my GPU at Linux - I always get Input/Output error.
Would like to try FreeBSD. Please tell, how to dump Video BIOS of my GPU at FreeBSD?
Is it impossible??? I thought that FreeBSD could do everything that Linux, and more! Am I wrong?
qmastery This board consists of mostly sysadmins, some programmers, some serious hobbyists and a sprinkling of FreeBSD devs on occasion but this is a Friday night. For specialized, technical information, you are more likely to get an answer on the IRC channel or the mailing lists.

Yes, anything Linux can do, FreeBSD does more and better.
I wrote about doing that years ago for the Matrox boards. It's in the mailing list archives somewhere. Seems unlikely to be useful today, though.