Re: [Qemu-discuss] TSC-Deadline x86 CPU Feature

[Ryan Roberts]

I never saw any response to this question - thought I would try once more 
before giving up!

> On 17 Apr 2019, at 00:53, Ryan Roberts <address@hidden> wrote:
> 
> Hi,
> 
> I'm trying to use qemu to do some OS development and need access to the x86 
> TSC-Deadline feature. I'm working on Windows and have tried version 3.1.0 in 
> both WSL (Windows Subsystem for Linux) using TCG and the native Windows build 
> using HAX. I've set the CPU to Skylake-Client (which I believe natively 
> supports TSC-Deadline). But in all of these scenarios CPUID does not report 
> the feature. TCG does throw out a warning ("warning: TCG doesn't support 
> requested feature: CPUID.01H:ECX.tsc-deadline [bit 24]") so I guess this is 
> expected behaviour, but for HAX my understanding is that it is using the 
> underlying HW virtualization support (I'm running on an i7 8th Gen which 
> definitely supports TSC-Deadline).
> 
> Does anybody know what I might be doing wrong here? Or perhaps the answer is 
> that it is only supported with KVM and I will not be able to simulate this 
> feature in a Windows host environment?
> 
> command line: qemu-system-x86_64.exe -m 10M -nographic -cdrom 
> build_dbg/bstp/env/baremetal/isa/x86_32/fwi/multiboot/pk.iso -accel hax -cpu 
> Skylake-Client
> 
> Thanks,
> Ryan
>