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?