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

Jonathan McDowell noodles at earth.li
Wed Mar 29 19:36:13 BST 2006

On Wed, Mar 29, 2006 at 02:46:05PM +0100, David Given wrote:
> 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.

It won't run more than a 16K block, which is too small for u-boot. I
think it might run a bigger compressed block (LDR is bigger, for
example), but I'm not quite sure it'll stretch to the 80 or so K my
current u-boot image is.

> 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.

FWIW my dmesg seems to show Linux picking up badblocks just fine, though
I can't confirm they're the same as what PBL sees.

> > 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?

make ams_delta_defconfig

with the patches that are there will give you a default .config which I
think is exactly what I used to build the image, or certainly not wildly

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

Really? It picks them up fine for me. If I do:

setenv bootargs mem=32M console=ttyS0,115200n8 root=/dev/ram0 initrd=0x11c00000,4M
bootm 11d00000

then I find the image uses the supplied initrd as expected.


/-\                             |    I'm not popular enough to be
|@/  Debian GNU/Linux Developer |             different.
\-                              |
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