[Info-vax] x86-64 XSAVE not available in Oracle VirtualBox when Microsoft Hyper-V is Enabled

[Andrew Brehm]

On 25/10/2021 13:02, Bob Gezelter wrote:> A cautionary note for those of us who use Oracle Virtual Box and
> other Virtual Machines on our Windows systems to run OpenVMS x86-64.
> Microsoft's Hyper-V, an issue recognized by Microsoft in
> "Virtualization applications don't work together with Hyper-V, Device
> Guard, and Credential Guard" available at
> https://docs.microsoft.com/en-us/troubleshoot/windows-client/application-management/virtualization-apps-not-work-with-hyper-v
>
>  For those running OpenVMS x86-64 the cautionary note is that the CPU
> Check Python script cannot see that Hyper-V is present. Oracle
> VirtualBox does not give a warning. When OpenVMS attempts to
> bootstrap, the bootstrap will detect the problem and abort with an
> error message.
> 
> The solution is to disable Hyper-V, per the instructions in the
> Microsoft article. One may not be aware that Hyper-V is active, as
> there are reportedly certain situations where Hyper-V may be
> installed without clear warning of its presence.
> 
> The problem is encountered when a guest operating system attempts to
> use affected facilities such as XSAVE. There is often no indicator
> that there is an issue until a guest operating system, e.g., OpenVMS
> x86-64 attempts to use the conflicted feature.
> 
> This would seem to be more of an oversight than an inherent problem.
> As an industry, how to deal with this has been understood before the
> advent of IBM's VM/360, in the 1960's. When I started system
> programming OS/360 and HASP in the mid-1970s, sharing  hardware
> feature between physical devices and simulated devices was well
> understood, the example being the HASP print, punch, and read pseudo
> devices.
> 
VirtualBox now works within the Hyper-V parent VM:

https://www.virtualbox.org/manual/UserManual.html#hyperv-support

I think I have actually tried that.

I use VirtualBox to run OS/2 since OS/2 will never run in Hyper-V directly.