Pbuilder-uml uses a user-mode-linux system, and builds debian packages inside the uml image. it is an ideal system to use to check that a package has correct build-dependencies. it uses apt extensively, and a local mirror, or a fast connection to a debian mirror is ideal, but not necessary.

requires user-mode-linux to function correctly

"pbuilder-user-mode-linux create" uses rootstrap to create uml image

"pbuilder-user-mode-linux update" updates the image to the current state of testing/unstable/whatever

"pbuilder-user-mode-linux build" takes a *.dsc file and builds a binary in the uml