HVF (hypervisor framework) support in Big Sur

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PeterHolbrook
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HVF (hypervisor framework) support in Big Sur

Post by PeterHolbrook »

Hi. Can anyone explain what practical advantages, if any, would derive from adding -accel=hvf to the qemu launch command line? I understand that, for this work in Big Sur, the qemu executable must be codesigned. Can anyone elaborate?
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Cat_7
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Re: HVF (hypervisor framework) support in Big Sur

Post by Cat_7 »

Hi,

For all I know:
The hypervisor on macOS (as haxm on Windows, or kvm on Linux) would help speed up operations IF the guest os architecture would be the same as the host os archictecture. This is clearly not the case when emulating powerpc on intel or arm.

I've seen this argument for the compiler appear in some places, it is non-sense to me.

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Cat_7
PeterHolbrook
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Re: HVF (hypervisor framework) support in Big Sur

Post by PeterHolbrook »

^Many thanks for your very reasonable explanation.
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Cat_7
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Re: HVF (hypervisor framework) support in Big Sur

Post by Cat_7 »

Here is the proof that this has no effect when compiling in Big Sur (intel):

./configure --target-list="ppc-softmmu" --enable-hvf

Targets and accelerators
KVM support: NO
HAX support: NO
HVF support: NO
WHPX support: NO
Xen support: NO
TCG support: YES

And that last option is what we have been using all along.

Running a binary that was compiled with --enable-hvf results in an error: -accel=hvf: invalid option.

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Cat_7
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adespoton
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Re: HVF (hypervisor framework) support in Big Sur

Post by adespoton »

Yup; HVF is the native HyperVisor framework, which allows passthrough of some hardware and registers in a secure and controlled manner. But if the CPU isn't being used in native mode, doing this makes no sense. So it works for QEMU-IA64 on Intel Mac targets, and it works for QEMU-AARCH64 on M1 targets, but in any other configuration, the compiler will either error out or override the config flag.
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