OS/2, eCS & ArcaOS - Technical > Utilities

VirtualBox, OS/2 guest, running with > 1 core. Success !?



my past experience with Virtualbox and running an OS/2 guest with > 1 core was that VirtualBox would hang very quickly and I always had to revert back to 1 core.

With Virtualbox 6.1.32 which was recently released, I find this in the change log:

--- Quote ---VMM: Workaround for OS/2 guest unstability on newer AMD CPUs due to a missing TLB flush in OS/2 (bug #20625)
--- End quote ---

My host OS is Win 10 and my CPU is an Intel 8-core but I thought "so what, just give it a try" and I activated 2 cores for the OS/2 guest virtual machine.
And lo and behold, it seems to work ok. As a test, I rebuilt my complete USB driver stack which starts quite a few parallel processes (I think nmake starts multiple processes if the dependencies allow) and that always used to hang pretty quickly in the past when using > 1 core.

So, I believe this not just fixes a problem with AMD CPUs but a general problem with handling the TLB, at least for OS/2 guests (I suppose this somehow interacts with OS/2 memory management where the OS/2 memory management might have some pecularities which make it distinct).

Can somebody confirm that ?

Martin Iturbide:
Hi Lars

I also had 1 processor on my ArcaOS VM, since I remember that it produced hanging to have several processors.

After your post I tried on VirtualBox 6.1.30 (Win10 Host) to increase to 2 processors and the VM is working fine for the moment.
Anyways I will be updating it to version 6.1.32 also.

Thanks for the "heads up".


Martin Iturbide:

I'm checking also the change log. Related to OS/2 it lists:

- VMM: Workaround for OS/2 guest unstability on newer AMD CPUs due to a missing TLB flush in OS/2 (bug #20625)
- OS/2 Additions: Fixed some issues with extended attributes in the shared folders (bug #19453)

But ArcaOS was also added to the list of OSes when you create a New VM. I will need to test that out.


Martin Iturbide:

It seems I felt slept with this ticket. (https://www.virtualbox.org/ticket/20741). AHCI was not accepted since it is not the default on the ArcaOS install. (It is needed to manually boot with " boot with menu" and select AHCI).


Unfortunately, even though > 1 core seems to work without hanging the system, the performance is hampered by I don't know what. After some time of usage, the system gets slower and slower and eventually, 1 core is then faster than > 1 core.
I'll revert back to the W4 kernel as an alternate boot config. That will limit to 1 core anyway and I'll keep around the main boot config with the SMP kernel and ACPI so that I can test in the future.


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