IXP1200 Board as a Peripheral

[Perry Wagle]

We are porting linux, with our mods, to the IXP1200.

We just got our IXP1200's last week.  I have one configured to
vxworks, and the other to angel.  With help from Dirk Brandewie at
Intel, we successfully did a LED helloworld with angel and angelboot
(ftp://ftp.netwinder.org/users/n/nico/).  My current task is hacking
the bios at (ftp://ftp.arm.linux.org.uk/pub/linux/arm/source/boot/) to
download via angel over serial-line to the card to then boot off the
network ala vxworks.  I'm hoping this approach will dovetail to
recreating and extending the stuff described below.

We've already got linux running on a SA110 (ebsa285 board).  Its a PCI
slave running on a Pentium Linux box.  Using the patches at
(ftp://nt4.el.utwente.nl/pub/co285/), I was able to get Linux kernel
2.3.24 (but not 2.2.12) to boot over the PCI bus.  To get this to go,
the ROM on the ebsa285 board needed to be reprogrammed, and the
kernels patched with the PCI mods that both permit the ebsa285 board
to be initialized and a kernel loaded over the PCI bus, and to provide
>>>IP-over-PCI<<<, which is then used to mount the root filesystem via
NFS.  Since this is a clean implementation of IP, it also permits the
host kernel to route packets outwards to other systems.

I'm rather taken with this IP-over-PCI, but it doesn't look like that
code is being maintained (last time stamp is June 1999), but I haven't
gotten around yet to querying the mailing lists to find out what the
deal is.  Having the root file system be accessible and modifiable by
other systems aids debugging: watch those timestamps change during
boot to see how far the boot sequence got; or watch the pci network
traffic via tcpdump.  You also get to build stuff on your
cross-development platform, and write directly to the filesystem
image.  I'm wondering how bad I want to maintain this stuff myself.

-- Perry Wagle (wagle at cse.ogi.edu)