Undocumented debugging facilities

Discussion created by Czerno on Mar 24, 2009
undocumented MSR debug

In AMD K7 and subsequent models, there happen to be hidden additional debugging facilities being controlled by (password protected!) MSR C0011024h  and sseq. It seems one can have the processor break conditionally upon data and/or address, full or partial match !

Please AMD (or anyone) tell where we can find the programming details, or do we have to experiment in the blind (and miss the better part) ?

It is unqualifiably dumb in my eyes to keep such useful processor functionality hidden (and, again! password protected) - I want to know every bit of MY processor (so it cannot be used AGAINST me!) and in this case, it cannot even be argued that the function is dangerous and/or reserved for BIOS developpers. So what's the point in hiding it ? What's the point in hiding /anything/ that could be a backdoor and I cannot check ?