On 1/29 2010 16:00:18 flameman wrote:

> > For _this_ kind of magic you have nearly whole 128MB. If you want 
> to
> > stay with kernel 1 boot, then you have 1.6MB.
> umm let me understand this part: do you mean by jtag, just to 
> shortcut
> things directly (jtag download byte directly into flash) ?

No, I mean the kind of magic if you write your own bootloader.

You can use NAND backup/restore to work with the whole 128MB.

The only area your bootloader probably cannot touch is the
device configuration area.

I never tried JTAG, but I think that production series of Spitz and
Akita are not equipped with the JTAG supporting bridge IC (see the
empty soldering pads on the teardown photos).

> i am supporting a ppc405GP board which has all the firmware in flash
> ... so i had to think about "Recovering a bricked board, using OCD
> Jtag programmer"

You cannot brick Spitz and Akita. PROM boot should always work.

> anybody has ever thought anything similar for akita ? Akita should
> have a jtag on his back, and jtag should be directly connected to
> PXA270 ... so it should be as standard as a pretty ARM databook 
> should
> explain.

No, it is not. There is just a serial IOPORT and few other wires.
I am not sure what is the purpose of connector under the battery cover.

> what i have not understand is:
> 1) is the flash area partitioned with slot0=1.6Mb,
> slot1=therest/whatever, and we can't re partion it into a whole 128Mb
> slot cause  ...cause  if we did it than we loose the nandutils&C that
> slot1 contains, so we loose a pretty procedure to re-flash if things
> go bad ?

No. slots are not partitions. Just the first partiton contains slots.
There should be:
NAND configuration block
NAND bootloader
slot for kernel 1
slot for kernel 2 (emergency aboot)

> 2) could we bypass it, just using jtag ? 1.6Mb is a pain in ... while
> i wish i could have 8Mb (or more) to handle a good (and nicer)
> bootloader + first aid kit (fsck, badblocks, RTC tools ... etc 
> etc ...

No, only new bootloader could bypass slot1 size.

> everything should be pretty useful for a pretty UNIX net install
> /maintenance/support)

You are not forced to use slot1 kernel as your primary kernel. You can 
use kexec (e. g. kexecboot) and boot anything you want.

> about my kexec-netboot, here is a shot-proof of concept
> (i need this bootloader, cause i net download the first aid kit into
> so call "early ram rootfs", also i like this bootloader cause i can
> test newkernel easier)

No, you don't need custom bootloader. You can learn netboot the kernel
in slot1. It would be much less work than programming the bootloader.

In fact, I think that nobody wa able to implement custom bootloader 

There are some proprietary things you would need to reverse-engineer
before being able to implement it:

- The way how PROM boot passes control to NAND boot.

- Completely initialize hardware, including things not initialized in
the current kernel (e. g. LCD phase settings).

Stanislav Brabec

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