I am working on the switch/routers that form the backbone of the Space
Station LAN (Joint Station LAN or JSL). The ppc processors that control the
switching fabric, perform the routing functions, SNMP, and all other
network functions are about 10 years old. Parts of the Flash have been
updated frequently for Firmware Upgrades. But the OS files (Linux
2.4.22-1.3 "Red Haggis" Kernel) have never been refreshed and are at the
end of the manufacture's data retention time. It looks like I may need to
cross-compile a stripped down version of busybox, load it into the ramdisk,
change root to the ramdisk, unmount then remount (?) the Flash drive to
make sure no files are active, then run a script to go through every file
in the system to copy it, md5sum old and new, if no errors delete the old
and rename the new.
From what I have read so far, this will require getting a copy of the
kernel header files, which the vendor of the card is not currently willing
to do. The next best would be to get the generic header files for this or a
close release and use those. I am also confused about this process. The
header files define the functions and variables, but not their address in
memory. I am assuming that dynamic linking to the kernel function happens
when the program starts, or are the function calls all sent to one address
which then determines which call was requested and branches of to the
correct code? Or is there another file(s) that contains the loader
information on the kernel routines and I will need to find or decipher that
too before a successful cross-compile can happen?
Sorry to dump a tough one on the group when I have added little recently,
but if I can get this going soon enough, it might actually get used on the
flight hardware. Otherwise it will be deemed a 'science project' and
cancelled in favor of just copying over the minimum number of system files
to run the script and using that instead of a stripped busy box. On the
other hand, if I can get this to work, I can also tweak the nandflash calls
to attempt to recover bad blocks that are only bad because the data aged
out. Currently, all the programs that work with nand flash don't allow any
interaction with marked bad blocks. But if the blocks only failed because
the data evaporated, a few write - erase cycles should freshen it back up
to being fully functional and probably just as reliable as the blocks that
hadn't aged out yet!
Mike
--
"Creativity is intelligence having fun." — Albert Einstein
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