The problem is that AMD CPUs have lots of bugs in their performance counter implementation. Intel CPUs don't have those bugs. With newer generations of AMD CPUs, AMD has fixed some of these bugs, but others remain.
I wonder why AMD hasn't stepped up to get involved in this project. There might be nothing that can be done with currently shipping silicon, but at least AMD could make sure that on their future silicon it all works. Fixing their performance counter bugs would likely benefit other projects as well.
Isn't this a sign that AMD's test suites are incomplete?
If they implement a feature correctly then break it in the new design, it suggests their test suites didn't exercise it properly, otherwise (you'd think) they would have caught the regression in the new design and fixed it before release.
The problem is that AMD CPUs have lots of bugs in their performance counter implementation. Intel CPUs don't have those bugs. With newer generations of AMD CPUs, AMD has fixed some of these bugs, but others remain.
I wonder why AMD hasn't stepped up to get involved in this project. There might be nothing that can be done with currently shipping silicon, but at least AMD could make sure that on their future silicon it all works. Fixing their performance counter bugs would likely benefit other projects as well.