Running colima with --arch x86_64 --vm-type=vz --vz-rosetta does not actually run Ubuntu VM on Rosetta

[maneesh29s]

I wanted to run the "guest" Ubuntu VM in x86_64 architecture, on rosetta.

At first I ran colima start -p ubuntu-arm --vm-type=vz --vz-rosetta, and then ran colima status, it showed that architecture is aarch64. I thought it would be x86_64 because Rosetta is used to emulate it on arm.

-> % colima status -p ubuntu-arm
INFO[0000] colima [profile=ubuntu-arm] is running using macOS Virtualization.Framework
INFO[0000] arch: aarch64
INFO[0000] runtime: docker
INFO[0000] mountType: virtiofs
INFO[0000] socket: unix:///Users/maneeshsutar/.colima/ubuntu-arm/docker.sock

In above case I could also see a com.apple.Virtualization.VirtualMachine process running in htop.

Then I added the extra option --arch x86_64, but then it started the VM with qemu engine.
As per lima's VM types docs, Rosetta is only supported on vz engine.
I got x86_64 Ubuntu, but it is very slow, as it is also mentioned in the lima docs.

Additionally, no com.apple.Virtualization.VirtualMachine process was running. In htop I could only see a qemu-system-x86_64 process running. This means that Rosetta was not running?

Another weird thing, runningcolima status on this new VM shows "running using macOS Virtualization.Framework"

-> % colima status -p ubuntu
INFO[0000] colima [profile=ubuntu] is running using macOS Virtualization.Framework
INFO[0000] arch: x86_64
INFO[0000] runtime: docker
INFO[0000] mountType: virtiofs
INFO[0000] socket: unix:///Users/maneeshsutar/.colima/ubuntu/docker.sock

Although no related process is running on my mac.

Just to compare, here's what we see in colima status, when colima is started using command colima start --arch x86_64 i.e. no options corresponding to rosetta:

-> % colima status -p ubuntu-true-x86
INFO[0000] colima [profile=ubuntu-true-x86] is running using QEMU
INFO[0000] arch: x86_64
INFO[0000] runtime: docker
INFO[0000] mountType: sshfs
INFO[0000] socket: unix:///Users/maneeshsutar/.colima/ubuntu-true-x86/docker.sock

I want to know if

1. Is it possible to run Ubuntu x86_64 guest VM using Rosetta? Or am I missing something? Does rosetta only work on a aarch64 Ubuntu guest OS?
2. The message in the status "running using macOS Virtualization.Framework", is that a bug?

[maneesh29s]

I got answer to my first question in this issue in lima's github
lima-vm/lima#2371

Lima only allows "aarch64" for VZ.
Thus when I pass --arch x86_64 colima falls back to qemu engine.

[maneesh29s]

For the 2nd question, I also found out the reason why colima status shows macOS virtualization being used.
Because in colima's Config.DriverLabel, the condition only checks if the VMtype is VZ. VMType is set to VZ as it is passed from the command line (--vm-type vz). But as mentioned before colima runs qemu engine when --arch x86_64 is also passed as option.

So the condition also needs to check if architecture is not x86_64.

[abiosoft]

Qemu is always available, so Colima will fall back to qemu when VZ requirements are not met.

However, I admit the user experience could be better and the behaviour can be more transparent by notifying the user accordingly.

[maneesh29s]

Thanks for responding.
I have raised an issue #1151 .