[Qemu-discuss] TSC-Deadline x86 CPU Feature

[Ryan Roberts]

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