USB Boot Drive

Note

Changing the opencore.vmdk means that upgrading will need extra steps to re-implement your changes.

The opencore.vmdk file is presented to the guest as a writeable USB drive. You can make it a read. only drive by changing a setting in the guest VMX file.

1. Make sure that the VM is shutdown and closed in VMware. You may want to ensure you do not have snapshots if this is a permanent change to the VM.
2. Open the VMX file, usually macos.vmx, in a text editor and change this line depending on what mode. you want:

usb_xhci:0.readonly = "TRUE" # Read write mode

usb_xhci:0.readonly = "FALSE" # Read only mode

3. Save the VMX file and then boot the VM

These changes can also be automated using the vmxtool in the tools folder, under the subfolder that matches your operating system. Note the you cannot have spaces around the "=" on the command line but they are added in the file.

Enable RW mode:

vmxtool set <vmx file> usb_xhci:0.readonly="FALSE"

Enable RO mode:

vmxtool set <vmx file> usb_xhci:0.readonly="TRUE"