Originally Posted by geekmaster
As you can see from the post above (if you are familiar with 5.1.x), it mounts a LOT more stuff (see all those loop mounts), and there is now twice as much space reserved for book indexes, so too many books will not brick your kindle like it did to many with the K4 and K5 were first introduced. And ENABLE_DIAGS does not work. And we do not know how to get into USB Downloader mode, so serial port debricking may be required for awhile. With these images, I am sure we will discover a lot more differences...
I had a quick look at those loop mounts and those are cramfs images of stuff we already had on 5.1.x. Cramfs images are compressed by default so they're saving some space, although I don't think that's the main reason why they used them. Maybe ease of update? Instead of updating several small files they can just update one big file?