New Build with Nested Virtualization in MacOS VM

[viskanic]

Hello everyone,

I want to build a new workstation for work and play.

The general idea of the workstation is to allow me to run Linux/Windows/MacOs on the same box, and switch between them depending on the use case.

Linux - as my default OS
Windows - as my gaming OS
MacOS - as my work OS

The first two I know how to setup, but the third one gets slightly more complicated.

As a mobile developer I need to be able to run multiple Simulators/Emulators of Mobile Devices inside MacOS, so I don't have to own multiple physical devices for debugging.

Questions:
1. Is this even possible at this moment in time ?

• I've already tried to make this run on a i5 6600k just to see if it would work.
• I've installed Macinabox and booted my MacOS instance, but as soon as I opened Android Studio, and wanted to start an emulator, I was greeted with the message "Your CPU does not support VT-x".
• I've already seen posts on the forum about enabling VM nesting in UNRAID, but this didn't help.

 

2. What hardware would you recommend ?

• I'm looking at the Ryzen 9 5950X, but since we are in the concept phase this is subject to change.

Any input is much appreciated.

Thank you.

Kind regards.

[ghost82]

1 hour ago, viskanic said:

Is this even possible at this moment in time ?

Nested virtualization in mac os is only possible with intel cpu (mac os doesn't support nested virtualization with amd):

you need to enable nested virtualization by:

 

1- add this line to syslinux configuration:

kvm_intel.nested=1

in the append line, so that it looks like:

append kvm_intel.nested=1 initrd=/bzroot

Reboot unraid

 

2- set up your mac os virtual machine for cpu passthrough: if you have the custom qemu arg at the end of the vm xml with penryn emulation nested virtualization will not work (it may work with other newer intel emulated cpu, I never tested); for cpu host passthrough you need:

  <qemu:commandline>
    ...
    ...
    ...
    <qemu:arg value='-cpu'/>
    <qemu:arg value='host, ....
  </qemu:commandline>
</domain>

 

Note that macinabox emulates penryn cpu, so if you didn't change the last lines of the xml to set the passthrough of the cpu, nested virtualization won't work.

Intel core 2 duo lacks EPT (extended page tables) and UG (unrestricted guest) for virtualization, this is why Penryn is not working.

Edited July 14, 2021 by ghost82

[viskanic]

Hi ghost82,

Thank you for your prompt reply.
 

20 hours ago, ghost82 said:

Nested virtualization in mac os is only possible with intel cpu (mac os doesn't support nested virtualization with amd)

So even though you could run MacOS on a AMD CPU and make it think you are using a Xeon,
when it comes to extra features like in my case nested virtualization, there is no workaround ?

That's dissapointing

So I guess my first choice for an Intel CPU with 16 cores, would be the i9 9960X.
It seems I just can't get away from Intels 14nm processors.

If you have any other thoughts or ideas, please feel free to share.

Kind regards.

[ghost82]

49 minutes ago, viskanic said:

So even though you could run MacOS on a AMD CPU and make it think you are using a Xeon,
when it comes to extra features like in my case nested virtualization, there is no workaround ?

I think so: I don't have any amd to test with, but to have nested virtualization in mac os you should need vt-x and amd has amd-v; if anyone has an amd cpu he can try to emulate a "Skylake-Client" cpu, but I would not bet it will work (I think that having virtualization working inside a vm is possible only with the passthrough of the cpu, and not possible to emulate, with an emulated cpu).

I know @david279 had a similar setup, if he's around maybe he tried and can confirm this with his amd cpu.

Edited July 15, 2021 by ghost82

[david279]

I used skylake-server with my setup but did not try anything with nested virtualization. I went bare metal hackintosh so I cannot test anything right now. 

[viskanic]

Hi @david279,

Thank you for your reply.

I was hoping not to run MacOS on bare metal.
Just to have a bit more control over the OS so an update doesn't mess up the installation.

I realise this is quite a niche requirement, but you can't blame me for trying

If anyone has any additional input, feel free to share.

Cheers.