Monday, January 02, 2012

Configuring a Hyper-V VM For Kernel Debugging

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   Yesterday's blog prompted some questions about how to set up a debugger for a Windows OS running in a Hyper-V VM.  I was surprised that I wasn't able to find good, publicly available, Microsoft issued documentation for this configuration.

The first step is to configure the Windows OS in the VM to enable a kernel debugger on COM1.  One would use these same steps if you were preparing the OS to be debugged using a null modem cable.  Hyper-V will allow us to redirect the COM port so that we don't need such a cable.

    Start an administrative command prompt.
    Turn on debugging with this command:

    bcdedit /debug on

    Configure the debugger to use COM1 with this command:

    bcdedit /dbgsettings SERIAL DEBUGPORT:1 BAUDRATE:115200


        Note that these are the default settings and already exist in most bcd stores.  However setting them again won't damage anything, and guards against a situation where the dbgsettings have been previously modified.

    Reboot so that the boot loader can read the new settings and configure the OS for debugging.


Read more: Ntdebugging Blog
QR: configuring-a-hyper-v-vm-for-kernel-debugging.aspx

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