s3c244x hardware ecc / backup kernel and rootfs direction

Werner Almesberger werner at openmoko.org
Thu Aug 14 05:24:03 CEST 2008

xiangfu wrote:
> read some mails that make me not sure the kboot  work  process.so i  
> write down my think
> tell me is it wrong.

What you wrote is perfectly correct :)

There still a few pieces we need in the first-stage loader, namely:

- boot from SD-card (that'll be mandatory in GTA03 but I don't think
  Andy will be happy unless we have it on GTA02 as well ;-)

- a way to switch between "normal" and "recovery" mode. This could
  be something like pressing down on the touch screen at reset time
  or holding down AUX or POWER for long enough, i.e.,

	void figleaf(void)
		if (power_button_is_pressed())

  We haven't discussed yet what would be the best way to enter the
  recovery mode on GTA02 (and later GTA03). Any opinions ?

  Some thoughts:

  - AUX would make this similar to what u-boot currently does and it's
    very easy to probe.

  - POWER would remove the overloading of AUX but it's harder to access.
    (In HXD8, we use POWER to access the u-boot boot menu, and this
    feels like a natural way to do this - actually better than what we
    currently have in GTA01/GTA02.)

  - The touch screen would be an input we haven't used at boot time yet.
    Not sure if we should.

- setting the NAND write-protect lock of GTA03. We need to decide on
  when to set it, and how to signal that it shouldn't be set.

  The radically simple approach: replicate the GTA02 situation and
  always set it. Someone who has a debug board can catch the boot
  loader before the lock is set and thus write to NAND.

  The artsy approach: bring up a grid on the screen and let users
  enter some unlocking code.

  Opinions ? There's no hurry - we have time to think about this one.

> then the first-stage have a name "figleaf" ?

Do you like it ? Anyone opposed ? :)

- Werner

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