Kindle firmware update 5.1.0 inserts two new (rarely used) fields into the eink update structure in front of critical fields that MUST be there. This completely breaks all existing programs that do eink updates using ioctl() calls, which is more important now that they removed the /proc for eink updates commonly used by programs and scripts in the past.
They created a major problem by relocating critical fields in this structure, because the 5.1.0 mxcfb.h uses the same filename and the same structure names as the 5.0.x header file, so you cannot include both of them.
Not only did lab126 break compatibility with other kindle models (i.e. K4diags), but they broke compatibility with the previous SUBVERSION of the K5 firmware, and "screwed the pooch" while they were getting busy in this new code...
It looks like I will have to keep using the old header file, and include renamed copies of the new severely flawed structure layout directly into my code. WTF were those guys smoking that day at lab126?