(I've initially intended to ask in the Linux-specific sub-forum, but I guess this is not limited to Linux only. Corrections welcome)
To be ready for un-bricking my horrible experiments that are bound to come, I'm slowly working on gathering information on how this wonderful creature boots.
Mrfixit (thanks!) clarified on IRC that the u-Boot bootloader is stored in an off-set on the eMMC, not directly accessible (~not in one of the two actual partitions, I assume).
So my questions would be:
- Where is it exactly?
- How do I find it?
- How do I recognize that I have actually found it?
I have also had a look at the ChromiumOS image, and in it, there are two interesting files in /boot: boot.scr and bootloader.bin.
(disclaimer: I'm away from the PBP and SD card, so I may be misremembering the filenames. Corrections will follow.)
When I run "file boot.scr", this is identified as an u-Boot bootloader image. The other file is simply data.
==> this brings a side-question: can the bootloader then be stored completely in the /boot partition? Or am I misunderstanding the purpose of these two files?
Upon further googling and reading, I've stumbled upon these links:
https://linux-sunxi.org/Bootable_SD_card
https://linux-sunxi.org/Mainline_U-Boot
These suggest specific places on the eMMC for the location of u-boot. I have also noticed that there are "gaps" at the beginning of the mmcblk1 disk and between the two "readable" partitions.
I've tried to copy various amounts of data from the above start locations using dd into a file and then tried to identify them with "file", but had no luck so far.
Am I looking into the wrong place?
Am I applying a completely wrong approach to find and identify u-Boot?
Ultimately, the question can be boiled down to: Once I have a u-Boot binary, where do I put it on the disk?
Apologies if these questions are too dumb, but I sort of figured this might be useful to document somewhere on the forums/wiki.
To be ready for un-bricking my horrible experiments that are bound to come, I'm slowly working on gathering information on how this wonderful creature boots.
Mrfixit (thanks!) clarified on IRC that the u-Boot bootloader is stored in an off-set on the eMMC, not directly accessible (~not in one of the two actual partitions, I assume).
So my questions would be:
- Where is it exactly?
- How do I find it?
- How do I recognize that I have actually found it?
I have also had a look at the ChromiumOS image, and in it, there are two interesting files in /boot: boot.scr and bootloader.bin.
(disclaimer: I'm away from the PBP and SD card, so I may be misremembering the filenames. Corrections will follow.)
When I run "file boot.scr", this is identified as an u-Boot bootloader image. The other file is simply data.
==> this brings a side-question: can the bootloader then be stored completely in the /boot partition? Or am I misunderstanding the purpose of these two files?
Upon further googling and reading, I've stumbled upon these links:
https://linux-sunxi.org/Bootable_SD_card
https://linux-sunxi.org/Mainline_U-Boot
These suggest specific places on the eMMC for the location of u-boot. I have also noticed that there are "gaps" at the beginning of the mmcblk1 disk and between the two "readable" partitions.
I've tried to copy various amounts of data from the above start locations using dd into a file and then tried to identify them with "file", but had no luck so far.
Am I looking into the wrong place?
Am I applying a completely wrong approach to find and identify u-Boot?
Ultimately, the question can be boiled down to: Once I have a u-Boot binary, where do I put it on the disk?
Apologies if these questions are too dumb, but I sort of figured this might be useful to document somewhere on the forums/wiki.
