CPU Reset will clear all debug features, except for reset break. This means for example that user-specified breakpoints will be invalid until the target halts once after reset. Note that this halt can be due to either a reset-break, or due to a user-initiated halt. In either case the debugger will restore the necessary debug features. SMM Entry/exit will disable/re-enable breakpoints, this means you cannot specify a breakpoint in SMRAM while halted outside of SMRAM. If you wish the break within SMRAM, you must first halt at the SMM entry-break and manually apply the breakpoint. Alternatively you can patch the BIOS to re-enable breakpoints when entering SMM, but this requires the ability to modify the BIOS which cannot be used in production code.