FWIW, I just added a
-H, --nightmode flag to
fbdepth to play with this. (EDIT: And fbgrab -v will output all you'll ever need to know about the fb state, including the grayscale flag. eips can do something similar, IIRC, but I never remember the syntax).
(I, err, never actually tried fbdepth on a Kindle, but I *should* have hidden the NTX quirks behind ifdefs

).
Every Kindle since the K5 (and the K4, technically

) will support the actual PxP inversion this requests (by which I mean to say that the only things missing on the KT4 are the fancy waveform modes and the fl shenanigans).
EDIT: This now ships as part of USBnet

.
@yparitcher: strace for
Rex &
Zelda. (For eInk stuff, you'll want to strace awesome on FW 5.x, and cvm on older devices. I usually go with
strace -fittv -e trace=ioctl -p $(pidof awesome)).
I don't rightly recall when the devcap stuff was added, but I would assume anything running FW 5.x should be fair game

.