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Re: FW: migrating from uClinux to emdebian crush on a Xscale PXA270 board



On Wed, 4 Feb 2009 10:58:34 +0100
"Hoefle Marco" <Marco.Hoefle@nanotronic.ch> wrote:

> Hello Neil,
> I filed a bug against the webpage:
> Bug#514101: Acknowledgement of maintainer-only report (buildd.emdebian.org confusing repositories)

Got it, thanks.

> I might have confused you in what I am doing and what I want to do,
> sorry about that. 

It's partially our fault for not making the website clearer. The
website does need to be made more helpful for new users, any other
issues that you find confusing, please file additional bugs.

> I am running emdebian-tools on a powerful pc which
> has debian lenny installed, so not on the actual target board. On this
> machine I think the emdebian-tool installation is correct now and
> emsetup works as well.

Ah, good.

> What I want to do is to get an emdebian demo running on a XScale PXA270
> board running which has 64MByte Ram and 32MByte flash. 

OK, I'm presuming that this board doesn't have a screen - what kind of
tasks / services do you want the board to provide once Emdebian Crush is
installed?

> On that board
> currently linux
> from Elinos (an embedded linux distributor) is running and I want to
> replace that. The linux kernel and the Elinos root filesystem is
> brought up by the boot loader uboot.
> So my question was if it is possible to replace the filesystem from
> elinos with that from emdebian I generated (the emdebian-arm.tgz) and
> to use the kernel already installed.

Safeguard the kernel modules first. Find out where the modules are
installed, collect them into a .tar.gz and put that tarball alongside
your emdebian-arm.tgz. I think you said that the kernel is on a
different part of the filesystem - as long as you can clear the storage
occupied by Elinos without removing the kernel then you can use that
kernel. If not, you'll need a way of either copying the current kernel
to your main machine and replacing it or a new kernel and installation
support.

I can't really be that much help with the specifics because each board
is so different. Hopefully some of the hardware experts on this list
will be more help. All I can offer is:
http://balloonboard.org/balloonwiki/BalloonSoftwareLoading

It's the only board that I have and the one I use to develop Emdebian
Crush.

> If it is not possible that easily imagine I would have a new empty
> device without anything. What would be the procedure to get emdebian
> running?

As long as the bootloader gives you a "development" mode where you have
a basic shell, access to utilities like mount, chroot etc., it should
be usable but each combination of bootloader and board is likely to
need bespoke scripting to actually do the installation.

buildroot provides a setup shell script that I use to actually install
emdebian:

http://www.balloonboard.org/lurker/message/20070712.172539.f3b9415a.ja.html

(Can't find the actual file online right now but the basic stage is to
clear the relevant partition, decompress the emdebian-arm.tgz tarball,
run ./emsecondstage, decompress the modules.tgz and reboot.)

But take a look at these files too:
http://balloonboard.org/cgi-bin/viewcvs.cgi/balloon/trunk/rootfs/debian/balloon3-config/files/

Wookey prepares a balloon3-config package from these. That config
package is then included into the emdebian-arm.tgz using
machine:variant support in emsandbox. The package provides a usable
inittab, fstab, modules list and a postinst maintainer script:

http://balloonboard.org/cgi-bin/viewcvs.cgi/balloon/trunk/rootfs/debian/balloon3-config/debian/postinst?rev=263&view=markup

These kind of board-specific config routines are needed to get the
board to boot successfully, but each routine is specific to one kind of
board. Hopefully, the working balloon implementation can act as a guide
for your board.

One of the reasons to release Emdebian Crush 1.0 alongside Lenny is to
get things like this standardised - to work out what works only for the
balloon and what works for other boards too.

Feel free to use the Debian Wiki to make notes of your progress:
http://wiki.debian.org/Embedded_Debian

Add a link to a new page in http://wiki.debian.org/EmdebianExamples and
click the link to create that page.

I'm hoping to get things like this folded into the normal Debian
Installer for the next Debian release - the more information you can
provide, the easier it will be to standardise the support before taking
it to D-I.

> I suppose first we need a bootloader installed on the flash, which one would you recommend?

Hopefully Wookey will jump in here and take over - I'm OK on the
software side but hardware and bootloaders are still difficult for me
too.

-- 


Neil Williams
=============
http://www.data-freedom.org/
http://www.nosoftwarepatents.com/
http://www.linux.codehelp.co.uk/

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