No subject

[Mike Bushroe]

Douglas,
  I will try to look you up! That may help me figure out faster whether or
not this is a lost cause!

The Kernel is coded into NOR flash, and the powers that be are VERY
hesitant to change it in any way for fear of bricking another unit. That is
despite the fact that a previous firmware rev required an update of the
kernel in NOR, so we have complete binary images of the up/down grade and
the software to burn them in. Of course, that only works if you can still
boot to the OS! If we make a minor mistake, we currently have no way to fix
it other than send it back to the vendor to reflash it, and management
would be very unhappy at the expense.

  From what I can tell, the NOR flash compressed kernel image goes most,
but not quite all of the way through the boot process. It does install
yaffs so that the final boot code can be read from /boot, but I think it
loads more by that point than usual. At the very least, it can output an
error message on the serial port if the NAND flash fails. But not enough to
run even basic recovery functions like cp or tar.

   The ttylinux sounds interesting, and the busybox too. I donwloaded a
pre-compiled busybox for the ppc, and it was over 1Mbyte, which is bigger
than the ramdisk we have to work with. I was hoping that stripping out
almost everything but tar, ssh, scp, cp, mv, rm, md5sum and a few others we
could get one small enough to load into the ramdisk after normal system
boot and then use chroot to have the system use the ramdisk busybox instead
of the normal bin and sbin files.

  I worst comes to worst, and it sounds like building a cross compiler is
already bad enough, we can also try coping the critical system files to the
ramdisk and then using chroot. It may take some trial and error to find out
all the files that need to be copied over. But then there would be no need
to cross compile, the programs already run on the system. I just wasn't
sure which approach would be more difficult and/or risky. But if building a
cross compiling environment will take forever and it doesn't take too many
files copied over to keep the system running, than using the existing code
but running from the ramdisk may be the best way to go. Pity, building the
cross-compiler sounded interesting. I just can't get approval for a 6 month
science project!

Mike

*Author: *Douglas Jerome <douglas at ttylinux.org>
> *Date: *2014-05-13 20:07 -700
> *To: *Main PLUG discussion list <plug-discuss at lists.phxlinux.org>
> *Subject: *Re: Anyone with experience in Cross-Compiling, especially to
> an embedded powerPC?
> Hi, Mike:
>
> I had been making my own set of gcc cross-compilers to cross-build
> my ttylinux distribution, but I've switched to using crosstool-ng.
>
> Maybe ttylinux can help you in some way, maybe with some
> modifications; it is fairly easy to hack(I say that but I made it).
> ttylinux is basically a cross-built kernel and busybox; it boots to
> RAM Disk and has an install script that transfers the whole system
> to a flash drive.
> http://ttylinux.net/
>
> Look me up. I work in the same building you do.
>

-- 
"Creativity is intelligence having fun." — Albert Einstein
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