smc_config.bin .. question

[boflc]

first, thank you all; to date, i've lurked around for a long time, and always have been able to find the answer i've been looking for.

i've recently been attempting to script-away smc config thermal changes; all 6 temperatures are straightforward to find and modify in smc_config.bin;

however.. i'm missing something, and i'm betting it's obvious to some but beyond my comprehension.

when i modify the thermals via 360 Flash Dump Tool v0.97, the first byte of the resulting image's smc_config.bin changes, and not obviously.

while its straightforward for me to modify the thermals themselves, i'm not certain what to tweak the first byte with -- i'm guessing it's a checksum of sorts, but .. beyond me.

would anyone be kind enough to nudge me in the right direction?

[l_oliveira]

It is an two byte checksum, indeed. I think you just need the checksum algorithm now...   

I could tell you ... If I knew how it worked. But hopefully someone who knows how it work will post here.

[cory1492]

The code has been posted on this board before, IIRC in the flash tool thread.

[fraggrrl]

http://www.xboxhacker.org/index.php?topic=13009.msg108930#msg108930

[boflc]

thanks; now to replicate this in tcl :O

once i saw "checksum" and cory validated it, it made the search easier. 

fraggrrl, thanks for the link, now i don't have to post it

[boflc]

sorted out.

spent way too much time (and a good friend's time) thinking my implementation of the algo was wrong -- b/c i interpreted the start of the smcconfig to be as q36 outlined in the follow-up post where he said:
  first 4 bytes are checksum, then 4 bytes version(FFFFFFFF) not used? , 5 bytes first power on date (FFFFFFFFFF) not used?, 1 byte reserved (FF). then smc config.

then after staring at the monitor for way too long, i re-read your post, cory, and saw offset 0x10 staring me right in the face.

anyway, sorted, and thank you.