Quote:
Originally Posted by nigredo
Finally some light... inclusive about why I got so confused.
The famous USB boot mode happens at reset, so we are with a cpu uninitialized, no dreams.
In this case: upload a uboot, upload a kernel+initramfs, run uboot that run the kernel.
At this point some people change the protocol from Serial Download Protocol to Updater Transport Protocol (the one used by utp_com, but mfgtool use too), but having a kernel there are more options.
UTP is based on SCSI messages, freescale has a kernel module that create a /dev/something.
Then a userspace daemon/program can communicate and handle the (few) commands, erase, flash etc. and can pass the commands to the shell too, or whatever.
UTP can be used on a normal running system (having the module), but I don't know if lab126 implemented it. I'll try to modify utp_com and see if there are answers when kindle is in normal state.
Update: I checked the kernel config, the module is disabled...
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Anything that you learn is more than we know here, so whatever time you spend is not wasted.
I have read (a small) bit of the Lab126 u-boot code -
And learned things like:
The voltage regulators are shut down (but u-boot finishes the SoC initialization).
I suspect that the on-chip boot code will jump to the USB download state with only OCRAM availabe (no dynamic ram start-up yet) -
ready to read the DCD (SoC hardware set-up) file.
Note: Just a few threads down in the index here is someone who has done better than "erase all" - their Kindle can not even init the dynamic ram.
So we have a use for anything learned here from that point on.
There is (or was) a separate manual posted @ Freescale about the on-chip to off-chip boot sequence.
One note: "Secure Boot" is disabled in the Kindle's SoC, one less thing to be worried about (that is from one of the log files posted in this thread).
There is no telling what NXP Semiconductors is going to do about the i.MX?? documentation and git repositories.
Note:
NXP Semiconductor purchased the firm previously known as Freescale Semiconductor last December 7th.
Freescale Semiconductor was the name of the firm previously known as Motorola.
I doubt that NXP will drop the i.MX6 product line (the newest line, with a very big customer (Amazon) ) - -
But that doesn't say anything about what will happen to the support available to non-customers.
In fact, I would not be surprised if we hear that Jeff Bezos has purchased a large chunk of NXP stock, just to be sure that the i.MX6 product line doesn't 'get lost' in the ownership transition. (It would probable be a smart move for Amazon to make.)
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Note to the casual reader:
These recent posts are not 'off topic' - this stuff is all related.