PW2 Why don't downgrades work after 5.8.7.x?

557 · 03-07-2019, 04:58 AM

Do we know what Amazon patched out of the firmware to prevent downgrading after 5.8.7? I've been trying to figure it out by comparing different OTA bins using NiLuJe's KindleTool but I haven't found anything. I'll probably end up doing the serial port method (I'm on PW2 firmware 5.10.3) but it would be nice to figure out a software jailbreak again.

knc1 · 03-07-2019, 05:23 AM

It is not in the binary(ies).
It is a scripting change, look there.
Last I looked, it was one commented out line with a one line comment on the change.

And if you could cause it to change before being jail broken, then you would not need our jail break.

557 · 03-07-2019, 05:33 AM

Thanks for the clues, I'll keep looking

NiLuJe · 03-07-2019, 10:14 AM

Both the ota facilities were updated, as well as the factory updater itself.

The former lives in various libraries & binaries in the main fs, while the latter is embedded in the kernel's initramfs. (i.e., you'll need a decent disassembler in all cases, as well as the right script/method to pull the initramfs out of an uboot kernel image. There's a couple mentions of this over here, but I don't recall how well that worked with current kernels).

knc1 · 03-07-2019, 02:08 PM

The newest kernels are "Device Table" layout.
I haven't posted a step-by-step for kernels with that layout.
(Don't hold your breath, I got so little user feedback on what I did post that I will probably never do this task again, so ask Google.)

NiLuJe · 03-07-2019, 03:56 PM

True, I'd forgotten about the backup thing.

So, yeah, in the meantime, the easiest way to get at the kernel image is probably to just pull it from an update package

.

03-07-2019, 04:58 AM	#1
557 Junior Member Posts: 4 Karma: 10 Join Date: Mar 2019 Device: PW2	Why don't downgrades work after 5.8.7.x? Do we know what Amazon patched out of the firmware to prevent downgrading after 5.8.7? I've been trying to figure it out by comparing different OTA bins using NiLuJe's KindleTool but I haven't found anything. I'll probably end up doing the serial port method (I'm on PW2 firmware 5.10.3) but it would be nice to figure out a software jailbreak again.

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03-07-2019, 05:23 AM	#2
knc1 Going Viral Posts: 17,212 Karma: 18210809 Join Date: Feb 2012 Location: Central Texas Device: No K1, PW2, KV, KOA	It is not in the binary(ies). It is a scripting change, look there. Last I looked, it was one commented out line with a one line comment on the change. And if you could cause it to change before being jail broken, then you would not need our jail break.

03-07-2019, 05:33 AM	#3
557 Junior Member Posts: 4 Karma: 10 Join Date: Mar 2019 Device: PW2	Thanks for the clues, I'll keep looking

03-07-2019, 10:14 AM	#4
NiLuJe BLAM! Posts: 13,480 Karma: 26012494 Join Date: Jun 2010 Location: Paris, France Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E	Both the ota facilities were updated, as well as the factory updater itself. The former lives in various libraries & binaries in the main fs, while the latter is embedded in the kernel's initramfs. (i.e., you'll need a decent disassembler in all cases, as well as the right script/method to pull the initramfs out of an uboot kernel image. There's a couple mentions of this over here, but I don't recall how well that worked with current kernels).

03-07-2019, 02:08 PM	#5
knc1 Going Viral Posts: 17,212 Karma: 18210809 Join Date: Feb 2012 Location: Central Texas Device: No K1, PW2, KV, KOA	The newest kernels are "Device Table" layout. I haven't posted a step-by-step for kernels with that layout. (Don't hold your breath, I got so little user feedback on what I did post that I will probably never do this task again, so ask Google.)

03-07-2019, 03:56 PM	#6
NiLuJe BLAM! Posts: 13,480 Karma: 26012494 Join Date: Jun 2010 Location: Paris, France Device: Kindle 2i, 3g, 4, 5w, PW, PW2, PW5; Kobo H2O, Forma, Elipsa, Sage, C2E	True, I'd forgotten about the backup thing. So, yeah, in the meantime, the easiest way to get at the kernel image is probably to just pull it from an update package .

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