Re: [Qemu-devel] Cannot launch QEMU with -accel whpx

[Justin Terry (VM)]

Hey Wenchao,

It looks like your specs should fully support running this. Did you by chance 
forget to enable the Windows optional feature? Having the lib/dll’s from the 
SDK isn’t all you need.

Try:
(admin) PS> Enable-WindowsOptionalFeature -Online -FeatureName 
HypervisorPlatform
(reboot the machine)
> qemu-system-x86_64.exe -accel whpx …

Let me know if that wasn’t the issue.

Thanks,
Justin

From: Wang Wenchao <address@hidden>
Sent: Thursday, April 26, 2018 3:47 AM
To: Justin Terry (VM) <address@hidden>
Cc: address@hidden
Subject: Cannot launch QEMU with -accel whpx

Hi, Justin,

We are interested in WHPX but haven't got it to work. We were able to build 
QEMU with WHPX support. We used MSYS2 build environment plus two libraries 
(WinHv*.lib) from the latest Windows 10 SDK Insider Preview to build QEMU and 
added '--enable-whpx' parameter in config. But when we ran it on Windows with 
Hyper-V on, QEMU failed to be launched.

The command to launch QEMU is as below,

> qemu-system-x86_64.exe -accel whpx

The following errors were output from the command line,

qemu-system-x86_64.exe: WHPX: No accelerator found, hr=00000000
qemu-system-x86_64.exe: failed to initialize WHPX: No space left on device

We analyzed the issue and found when invoking the Windows Hypervisor Platform 
API WHvGetCapability(), it returned whpx_cap.HypervisorPresent with FALSE and 
then WHPX failed to initialize. Do you have any suggestion on that? Thanks.

We build and run QEMU on the same machine. Below are its specs,

Windows OS: Windows 10 Insider Preview
Windows edition: Professional
Windows version: 1803 (OS build 17133.1)
SDK version: 10.0.17125.0

Processor: Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz 1.99GHz
RAM: 8.00 GB
System Type: 64-bit Operating System, x64-based processor


Best Regards,
Wenchao