[E3-hacking] PBL and flash access on the E3

David Given dg at cowlark.com
Wed Mar 29 14:46:05 BST 2006

Hash: SHA1

Jonathan McDowell wrote:
> I'm not entirely sure if PBL will read a LDR block earlier than 4M into
> flash; need to test that. And I seemed to be getting issues with the
> tail end of flash, so I need to have a look and see if PBL writes
> anything there that I might have to avoid. Aside from that does this
> seem sane to people?

PBL on the E2 certainly has a rather small limit as to the size of an
executable block (too small to use for a Linux kernel, maybe too small
for u-boot --- I forget the exact size). I don't know if the E3 has the
same issue.

Thanks to Cliff for the detailed explanation of how the flash metadata
works. From that, it seems to me that the view of the flash that PBL
sees (after bad-block remapping) is *not* the same as the view that
Linux sees (talking directly to the chip). Which means that while I'm
safe and won't be able to trash the metadata using PBL, I *will* be able
to trash the metadata using Linux --- and if I trash the metadata, I
won't be able to use PBL to boot from the flash.

Could the strange issues at the end of the flash be this metadata?

> Jonath*a*n. (I'm on a mission to educate the world about how to spell my
> name.)

Oops --- sorry!

I'm reminded of Iain Banks talking about how to spell his name. 'Iain',
he says, is a totally different name from 'Ian'. 'Iain' is the correct
version. 'Ian', however, is simply an erroneous abbreviation for
'Cyclopian', which as everybody knows means 'to have only one I'...

> I've updated the prebuilt kernel to include the palette fixing patch and
> also enable the internal modem.

Ta, I will fetch it. Is there any chance of uploading the kernel
configuration file, as well, so I can try to build my own?

(Also, you may be interested to know that the kernel seems to be
ignoring the boot parameters passed to it by u-boot.)

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