Originally Posted by Poetcop
Psyched you're making progress on this geekmaster!
I just took another look at this with the serial port connected.
When it is in fastboot mode, if you disconnect the USB cable it immediately drops to a bist> prompt at the serial port, waiting for you to type a bist command.
So... we now know that you cannot stay in fastboot mode and change computers (but it does work well for me dropping into and out of a VM, because the kindle USB port does not lose power.
While typing this I got an idea: put a powered USB hub between the kindle and host PC so the kindle sees power while switching the hub usb cable between a windows host PC and a linux host PC.
Just need to find a powered USB hub around here somewhere (a LONG time since I used one)...
EDIT: If the powered USB hub helps the kindle stay in fastboot mode while changing host PC, this will be a MUCH easier method than trying to debug the custom u-boot to see why fastboot mode is not surviving a kindle reboot. I cannot locate a powered USB hub right now, so I requested help in a new thread to test this to see if we can use a powered USB hub to switch host PCs while staying in fastboot mode.
UPDATE: I realized that one of the LCD displays sitting in front of me has a built-in powered USB hub. I tested it. It did not work. So... we still need a way to make u-boot permanently change the idme bootmode var to "fastboot" (until you change it to something else later). For now, the only way to do this is to run either linux or windows in a Virtual Machine (emulator), or to get fastboot working in cygwin on windows.
*** Has anybody gotten the cygwin version of yifanlu's kindle fastboot tool working correctly?