What it happens is the virtual CPU stop working because the hypervisor is not supporting the CPU. If you don't need virtualization you can download this version of Windows Server, but if you need the virtualization you should get the Workstation version with VT-x.
The Workstation version is the last one with support for VT-x
I would have thought that for it to work on an x86 processor, you'd need to have vmx support - as you have. However, for the sake of completeness, there are other ways to virtualize (with emulation only) x86-64 processors that don't require vmx.
What is vmx and what exactly is missing? It doesn't look like there's anything beyond VT-x emulation that's missing. It's not clear what you mean by kernel panic. Did you use vmware-vmx -nodetect to create the VM or are you using a VMX-enabled KVM host?
I'm running KVM with OpenSUSE 13.2 (which does not include VT-x support at all) and have no problems, although it's been a while since I created a VM.
This is probably the most appropriate way of using vmx on an x86 64-bit processor.
The only way of emulating a vmx is the kernel level switching (vmx-k), but it is using the operating system scheduler as emulator (only). The problem is that it is not the same as the vmx using with hypervisor (vmware-vmx -nodetect).
If you need a VM using with the hypervisor, the Workstation version includes the vmx-x. And the KVM does the same.
In this case, the Hypervisor makes a background switching on the kernel, and can schedule the vCPU (maybe changing its context to the context of a host CPU) without swapping the context in memory. The problem is that in any case you are using the Host OS's scheduler, and the virtual CPU does not start using its scheduler (even if with qemu-system-x86_64).
The problem in a hypervisor is that if the VM is using the x86-64 architecture, it can be switched on the Kernel if the hypervisor detect that the CPU is a x86-64. However, the scheduler is not initialized for x86-64 (I don't
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