D171 - An out-pointer that is never written has no signature

decided · 2026-08-21

sceSystemServiceParamGetInt answers a console setting through an out-pointer. Unimplemented, it wrote nothing, and the guest read whatever its stack held there.

That is a worse failure than a wrong return value, and worth separating from it. Every other unimplemented call in this project answers wrongly but consistently - the same placeholder every run, recognisable in a trace, in a range no real code occupies. An unwritten out-pointer answers differently on every run, depending on what last used that stack slot, and leaves nothing to recognise because nothing was written.

So orbistoun-systemservice exists and always writes. Zero is a stated placeholder rather than a value: read as an index it lands on the first entry, as a flag it reads as off, as a count it reads as none - all ordinary states a title must already handle. A non-zero guess would be picking a behaviour out of the air and calling it a default.

Success is reported rather than an error, deliberately: a guest that checks the return skips whatever the setting was for, while one that does not check reads the value regardless - which is why it must be written either way.

It did not move the wall. The call is reached, the implementation is correct, and image+0x43c4 is unchanged - so the hypothesis was wrong. Recorded because a wrong hypothesis that was cheap to test and left the code better is a fine outcome, and because the out-pointer class of failure is real whether or not it was this one.