A20 booting process

[vince66]

Hello everybody,

I'm new of this list. My question follows.

I'm interesting into the booting process of the A20. In particular i'd like to know if the firmware for booting is not active after the boot process.

The important thing for me is that the firmware is not used after boot and that the OS don't touch the HW; more precisely, i need that when a USB key or a SATA hard Disk is plugged after boot, the firmware won't have the chance to touch it.

After that with a simple:

dd if=/dev/sdX of=$HOME/usbkeyimage.raw bs=1M

I should have a bitstream copy of it (disk image).

Is it possible or is there a remote possibility (or edge cases) for wich the firmware make writing operations in the plugged drive ?

Thanks very much in advance.

Best Regards.

Vincenzo.

[SR-Digitronic]

Why should the bootloader write to a random USB device? I mean they could, but usually U-Boot only tries to load files.
The Secondary Bootloader (Das U-Boot) can access USB storage devices, but it does not run any longer when the Kernel is started. It's copy in your RAM should be even overwritten over time. (afaik!)
You only should make sure that the device isn't mounted, this means it does not work when you booted Linux from your flash drive or hard disk.

The boot process goes roughly like this:
NAND: BROM -> Boot0 -> Boot1 -> boot.axf -> U-Boot -> Linux Kernel
SD: BROM -> U-Boot SPL -> Linux Kernel

http://linux-sunxi.org/BROM