Hidden Debug Mode Found In AMD Processors
 

A hidden (and hardware password protected, by means of required special values in processor registers) debug mode has been found in AMD processors, and documented by a reverse engineer called Czernobyl on the RCE Forums community today. It enables powerful hardware debugging features long longed for by reverse engineers, such as hardware data-aware conditional breakpoints, and direct hardware 'page guard'-style breakpoints.

http://hardware.slashdot.org/story/1...t+%28rdf%29%29

Site is offline, but not very surprising, I know retail user have been looking into this before, I remember some thinking JTAG could maybe solve their locked processor issue's :)