I wanted to bring manual loading support to the SX20. I know it is stated a thousand times that CHDK does not support this for this camera, but it was never said why. I thought it was because no one has bothered finding the key/iv for it. So I spent hours crawling the ASM-jungle and when I finally found them, in the middle of my ecstasy (no complaint about the bad format of the update file anymore), I received the infamous E31 error. The CHDK splash screen even shows up a for a sec, and the camera turns off.
So, since this was never really answered before (or at least I could not find it nowhere after reading through all the related forums and wiki pages): Why doesn't it work? Does anybody know what is needed to make it work? I know some other cameras have the same problem, such as the G11. What is the exact reason for this "SUBCPU" error (which is overly annoying as it shows up permanently in the ver.req screen), which code in CHDK is responsible for it and what would have to be done to support manual loading on these cameras?