Build failure of VirtualBox Guest additions on arm64 machine with Ubuntu

[Jhankar]

I can see Ubuntu provides the iso image of Virtualbox guest addition but when I try to build it from the source code on an arm64 machine, it fails. Am I missing anything?

ubuntu@1pthunderx1-137:~/virtualbox-guest-additions/src/VirtualBox-6.1.6$ ./configure --nofatal --disable-dbus --disable-xpcom --disable-sdl-ttf --disable-pulse --disable-alsa --disable-kmods --build-headless

Checking for environment: ** Cannot determine system!

I made some fixes and went ahead. Now, the code stuck in include/iprt/cdefs.h:
error "Architecture identifier missing / not implemented."

Need to find the value of RT_VALID_PTR in the case of arm64.

[Martin]

Where did you get the idea that anything from VirtualBox would work with ARM?

[Jhankar]

I have seen the virtualbox-guest-additions-iso binary package in Ubuntu arm64. I can also install it on arm64 machine by "sudo apt-get install virtualbox-guest-additions-iso".
Could you tell what is the use of this package?

[mpack]

Ask Ubuntu - they include a fork of the GAs in the Ubuntu standard distro for reasons of their own. I imagine the source code contains lots of thing that aren't needed on ARM64.

And to be clear: VirtualBox is a virtualization supervisor, not a CPU simulator. An ARM64 doesn't even have those features to supervise, besides having a completely different instruction set and architecture.

[Jhankar]

We are trying to port the available source code for Virtualbox-guest-additions on arm64. Are there some virtualization concepts due to which it's not possible? Are we missing anything?

[Martin]

What benefits do you expect from the VirtualBox Guest Additions on arm64 when VirtualBox itself doesn't work on ARM?
You cannot run VirtualBox on ARM and therefore also no VirtualBox with an guest os built for ARM.

[Jhankar]

Why is it not possible to port VirtualBox on arm64? Is it because of some virtualization concepts?

[Martin]

It is a virtualizer which passes through directly the Intel/AMD CPU commands to the host. It isn't a simulator which would simulate an ARM CPU for a guest.

[mpack]

Why is it not possible to port VirtualBox on arm64? Is it because of some virtualization concepts?

You need to go do some basic research: a CPU simulator is an ENTIRELY DIFFERENT THING from a virtualizer, and VirtualBox is a virtualizer. You need a CPU simulator to run Intel code on an ARM, because those CPUs have incompatible architectures. That means you need something that is not VirtualBox.

To be clear: ignoring a few assembler modules that may exist, it should be possible to compile and link VirtualBox for ARM64, but it will do nothing useful, because VirtualBox is a tool which manages certain features of Intel/AMD processors.

[Jhankar]

It is a virtualizer which passes through directly the Intel/AMD CPU commands to the host. It isn't a simulator which would simulate an ARM CPU for a guest.

What are those Intel/Amd specific commands/features through which Virtualizer passes?

[mpack]

Why do I get the feeling that we're being trolled? The question has now been asked and answered multiple times in multiple ways, so I'm going to lock this topic.

If you still want to know what a hypervisor does, here's a good starting point start: https://en.wikipedia.org/wiki/Hardware_virtualization.