I couldn’t get much on this phrase. It is a weird one I know but I just can’t stand not knowing it. How did the current use of “at all” come into being?
Take a look at this:
“in any way,” mid-14c., originally used only affirmatively (as in I Sam. XX:6 in KJV: “If thy father at all misse me”); now it is overwhelmingly used only in the negative or in interrogatory expressions, or in literary attempts at Irish dialect.
Can this be trusted?
I think you may trust this. It is drawn from OED 1, 9.b., where you may see representative citations going back to ‘c 1350’.