Very simple question: does the new LBR_SELECT branch filtering capability (introduced in Nehalem) also apply to the BTF branch single-stepping or just LBR (Last Branch Record tracing)? The naming of the feature suggests the later, but I just wanted to make sure.
Being able to single-step in selected classes of branches (as opposed to all of them) would help me a lot with the work that I am doing.
I don't believe so. Typical usage of LBR is profiling, when the instruction stream is progressing normally, and a stack of LBR can capture branch addresses over a larger window of ip addresses. If you are already single-stepping, historical branch addressescould be captured bythe tool already withoutusing additional facility in the cpu hardware.