VMX and hardware debuggers

[jason09]

Is it possible to single-step from VMX non-root mode into VMX root mode using a hardware debugger? Or, barring that, are internal VMX registers, such as the current VMCS pointer, readable using a hardware debugger (so a BP can be set at the host entry point)? I'm trying to trace execution into and out of a very simple VT-x hypervisor.

[David_O_Intel1]

A fellow engineer commented:

"Kernel debuggers provide tracing capabilities between non-root and root modes.

One of the possibilities is to set 2 separate kernel debugger sessions: one - for root, another for non-root.

For example, for Hyper-V, the instance of kernel debugger that is responsible for the non-root execution runs inside RootOS using method that is known as VirtualPipe, the instance that traces Hyper-V execution is running on a separate machine that is connected to the unit under test (UUT) via 1394.

The above debug capabilities may require additional investigation/development."

David Ott

[hellfire]

Possible solution is adopting GDB stub for running in VMX root mode and exchanging via serial port with client at the other PC.