Re: Did the "TCG" emulation mode has a full capability compare with the "KVM" emulation mode?

["Alex Bennée" <alex.bennee@linaro.org>]

tugouxp <13824125580@163.com> writes:

> Hello folks:
>    I have a puzzle on qemu major two emuation implentions on whole system emulation, that is ,except the emuation speed,
> did the TCG work mode has any weakness than "KVM" work mode on whole system emulations(including kernek and
> user-space)?

It depends on the guest architecture. Some are more complete than
others. The x86 emulation for example doesn't cover all the modern x86
extensions although there have been some improvements to its vector
handling recently.

One thing TCG can do that KVM can't is emulate code running at higher
priority than kernel-mode. For example for ARM we can emulate the
EL3/Root domain and secure and confidential realms. In KVM you can only
run a guest EL1 kernel and its user space.

> is there any work that kvm can do but TCG cant? 
>
> of course kvm is much faster than TCG, but my question just about the funtion, not care about speed.
>
> thanks for your kindly help!
> BRs
> zilong.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro