This is a stream-of-consciousness document right now; edits (or comments in the Discussion tab above) are very welcome, if they can help to turn this into something a new developer can use to bootstrap. Windows-related commentary would be especially appreciated.
Most developers working on Evo ECU disassembly use some version of IDA Pro Advanced (the Standard and Freeware editions do not contain processor support for the SH processors in Evo ECUs).
Since most people aren't superhuman geeks, they tend to rely on an assembler for writing new code. KPIT Cummins provides a pre-built version of GNU binutils on their website, and on Windows, it integrates with their HEW environment nicely.
The KPIT tools also come with a program called sh-elf-objdump, which you may be able to use to do some VERY rudimentary disassembly.
For those just getting started with IDA, these tools may be useful (please note: they were developed on Linux, and assume a UNIX-like command line is available; on Windows, you will need something like Cygwin):
- Following the instructions at the beginning of the file should result in an IDA database that can be used to produce a .ASM file that GNU as can use, once you run it through pcrel_filter.sh.
- An sh/awk script that reads in an IDC-produced .ASM file, and produces (hopefully) output that GNU binutils can parse and re-assemble.
Once you have a workable .ASM output from pcrel_filter.sh, simply running sh-elf-as -o rom.o (filename.asm) (where (filename.asm) is your produced assembly output) will create a file named rom.o.
Then, run the linker: sh-elf-ld -o rom rom.o.
Finally, you'll need to use a command like dd if=rom of=rom.hex bs=1 skip=132 count=262144 to extract the ROM image you'll want for writing to your ECU.
To ensure that your resulting output is the same as the original input, you can run the command cmp rom.hex (original ROM image), where (original ROM image) is the filename of your original source data that you imported into IDA.
Other useful UNIX commands are hexdump (a flexible program for displaying binary data in a more useful format) and hexedit (a binary file editor).
If you only read one document about the Evo ECU hardware platform, read this one:
That is the original Renesas hardware manual for the SH-2 platform.
For looking up additional information, you should be aware that both the Evo VIII and IX use an SH2E processor; the Evo VIII uses an SH7052F platform, and the IX uses an SH7058F. One of the primary differences is that the Evo VIII has a 256KB ROM image, while the IX has a 512KB ROM.