What does this Xcode warning mean? "application executable is missing required architecture. ..."

Question

When I build & run my app for iOS 5 in Xcode 4.2 for my iPod touch 4th generation (the first one with retina display), I get this warning:

warning: iPhone/iPod Touch: application executable is missing a required architecture. At least one of the following architecture(s) must be present: armv6 (-19033)

Although it warned about a missing architecture, the app runs on my iPod touch. What am I supposed to do to get rid of this warning?

This is what I see in my build settings. There's no other architecture to choose from than armv7 (which I think was the special one for the iPhone 3GS and possibly all subsequent devices):

Answer 1

Manually add the string "armv6" (without quotes) as a new arch type (by double clicking the "Standard (armv7)" line, then click the + button at the bottom of the popup), and the error goes away after a "Clean", and "build".