[fedora-arm] Flash GuruPlug NAND without JTAG cable?

[Jon Hermansen]

Itamar,
 I have read over many guides, including the Fedora wiki, Ubuntu
ARM-specific wiki pages, plugcomputer.org, and a few other places but yet
have not found what I've been looking for. All the pages I've read
specifically refer to accessing U-Boot over serial (using the $40 box from
Global Scale, or I can DIY) from another PC, and I can't do this at the
moment. Specifically, I think the problem boils down to knowing specific
offsets to data on the NAND on my GuruPlug board.

There are existing tools that will supposedly do what I want -- flash
onboard NAND:
 1. mtd-utils: http://www.linux-mtd.infradead.org/
 2. sheeva-uboot-tools: http://code.google.com/p/sheeva-uboot-tools/

I assume that the latter tool relies on the former. Now, fw_printenv (part
of mtd-utils) always throws "bad CRC" at me because I haven't figured out
the correct offsets/sizes yet. I've done a nanddump on the partitions of the
MTD that have the interesting bits on them, namely, the u-boot loader and
the kernel. There is a third partition, that holds the rootfs:

[root at guru ~]# cat /proc/mtd
> dev:    size   erasesize  name
> mtd0: 00100000 00020000 "u-boot"
> mtd1: 00400000 00020000 "uImage"
> mtd2: 1fb00000 00020000 "root"
>

I looked at the uImage bit in a hex editor, and found nothing interesting or
configurable, just kernel junk. In the "u-boot" partition, I have found bits
that look like configuration information, but I _do not_ want to modify the
default u-boot options, in fact, I'd rather leave them in case I get a JTAG
cable later or do something to bork my OS. I also can't discern where in
this file lie the custom settings vs. the default settings, so I won't
change any bits here yet...

I have considered another alternative, that is, only flashing over the
uImage and rootfs MTD partitions. This would be fine, assuming that the
shipped version of U-Boot does not limit functionality on my system... and I
think this would allow me to install Fedora 12.

An additional alternative would be to fake passed parameters to the kernel,
i.e. hack the kernel source to default to "root=/dev/sda" and thus
overriding my current /proc/cmdline:

[root at guru ~]# cat /proc/cmdline
> console=ttyS0,115200 ubi.mtd=2 root=ubi0:rootfs rootfstype=ubifs
>

If anyone has any more information, please advise. I am considering writing
to Global Scale / the kernel developers over at Marvell to see if they can
drop me any hints...

On Sun, May 9, 2010 at 9:30 PM, Itamar Reis Peixoto <itamar at ispbrasil.com.br
> wrote:

> On Sun, May 9, 2010 at 3:46 AM, Jon Hermansen <jon.hermansen at gmail.com>
> wrote:
> > Hello all,
> >  I just got a brand new GuruPlug a few days ago and I was hoping to
> install
> > Fedora ARM on it as soon as possible. Well, the only problem is, I
> neglected
> > to get the JTAG breakout box / cables required to get the U-Boot prompt
> and
> > thus, as far as I can tell, can't do much about loading a new U-Boot
> version
> > (hopefully to boot from microSD), putting a new U-Boot config, Linux
> kernel
> > and accompanying rootfs on the NAND/external MicroSD card. I can see the
> > /dev/mtd* devices from Debian 5.0.3, kernel 2.6.32-00007-g56678ec, but I
> > have yet to write to them from my live system as I want to be absolutely
> > sure about what I'm doing on this front.
> >
> > I'd also like to know if I can use the internal NAND/external MicroSD
> card
> > as one big device, as opposed to two seperate devices. I realize the NAND
> is
> > not addressed as a block device, but if they both can contain
> filesystems,
> > does that mean that I can use UnionFS (or something similiar) to bridge
> two
> > seperate filesystems and divide the space taken up by data between the
> two
> > storage devices?
> >
> > If anyone could provide any more information on what I'm attempting to do
> > (flash NAND, reinstall OS) without a JTAG cable, either on a SheevaPlug
> or a
> > GuruPlug (from what I've read, they are nearly the same), it would be
> > greatly appreciated.
> >
> > Thanks to all of you guys for working out the kinks in Fedora ARM, and
> I'm
> > looking forward to using my favorite distro on the smallest PC I've ever
> > had...
> >
> > Jon Hermansen
> >
> start here -> https://fedoraproject.org/wiki/Architectures/ARM
>
>
> --
> ------------
>
> Itamar Reis Peixoto
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.fedoraproject.org/pipermail/arm/attachments/20100511/183c2cb5/attachment-0001.html