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Originally Posted by Dexmaster
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I have another idea of non-deletable FAT32 file (update.bin.tmp.partial) http://superuser.com/questions/42421...n-an-usb-drive , but I'm not sure it will help with Linux on Kindle and it's way to silently download OTA updates... What do you think? Do you have a fast way to test it out?
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Nice find.
I suppose we could think of that as the Windows version of "Immutable" - at least for our purposes.
I don't have a ready-to-run solution for setting those bits in the FAT32 directory -
But it should not be too hard to make one (maybe runnable via a KUAL menu entry).
If you have access to a Linux PC, then you can easily get a copy of the FAT32 backing store - including MBR, Partition table, Directory, and data area.
See:
https://www.mobileread.com/forums/sho...d.php?t=262358 (and maybe the older write-up).
And under Linux, that file copy of the backing store device can be used just as if it was a real device (that is what losetup does, a file -> device translation).
Handy for testing out utilities for diddling the FAT32 directory entries.
It will not matter to the final solution if the user only has Windows on their PC - we have Linux on the Kindle, which is where the bit diddle utility will eventual run.
And that may be where we have trouble - the Linux FAT32 driver may not respond the same way to those hidden bits that the Windows driver/system does.
But certainly worth spending some time trying it out.
If your going to downgrade and then let the device attempt to download the OTA update (hopefully aborting its download before it completes) -
One of the things to check for, is the '.tmp' sub-string part of the temporary filename.
It has been reported that perhaps 5.6.x does not include that in the temporary filename.
And that might be why the current Backdoor Lock fails (its expecting the wrong temporary filename).
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Note: to only diddle the directory entries - you only need the first 8196 bytes (two flash erase blocks, 16 logical sectors) of the backing store.
That will get you the FAT32 MBR, Partition table, and Directory (without the 2g data area).