topic Re: VMX and hardware debuggers in Software Archive

VMX and hardware debuggers

jason09 — Fri, 04 Dec 2009 14:48:10 GMT

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.

Re: VMX and hardware debuggers

David_O_Intel1 — Mon, 14 Dec 2009 22:18:28 GMT

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

Re: VMX and hardware debuggers

hellfire — Tue, 15 Dec 2009 07:19:26 GMT

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