Re: [Qemu-devel] did the qemu can emulate the whole system with the processor that without support the "virtulization and kvm"?

[tugouxp]

thank u.


>t can either use TCG or a HW based acceleration
>like KVM. HW based acceleration is only available on the same machine
>type.

BTW, if use the HW acceleration like KVM, no TCG translation between target 
instruction and host instruction happened, right?

thanks!








At 2018-12-21 22:14:58, "Alex Bennée" <address@hidden> wrote:
>
>tugouxp <address@hidden> writes:
>
>> thank you.
>>
>> i just want to confirm one thing,  that is whether the qemu can emulate a 
>> whole operation system just by analysis instructions by instructions 
>> manually  without the support of KVM.
>> so from the answer you give to me, it is feasible, right?
>
>Yes - if you run qemu-system-$(ARCH) you are emulating a full machine
>with hardware attached. It can either use TCG or a HW based acceleration
>like KVM. HW based acceleration is only available on the same machine
>type.
>
>There is a third type - qemu-$(ARCH) which is often called linux-user
>mode. Here the translation engine only translates instruction from guest
>to the host and then maps system calls to the host system. This is isn't
>emulating a whole system but allows you to run binaries from one
>architecture on another.
>
>>
>>
>>
>> thanks very much!
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> At 2018-12-21 17:01:02, "Alex Bennée" <address@hidden> wrote:
>>>
>>>tugouxp <address@hidden> writes:
>>>
>>>> Hi alex:
>>>>     now my host machine did not have the "/dev/kvm" nodes and no chance to 
>>>> make it exists.
>>>> so i want to know whether the "/dev/kvm" is  mandatory  for qemu to 
>>>> emulate the whole system.
>>>> so i can make the emulation without the support of kvm mechanism.
>>>
>>>QEMU runs in two modes - full system emulation with TCG doesn't require
>>>KVM although it is relatively slow. On systems where there guest
>>>architecture is the same as the host architecture you can run with KMV
>>>(or HAX/WHPX/HVF) accelerators at near native speeds.
>>>
>>>The reasons for not having a /dev/kvm can vary but you haven't said what
>>>your host architecture is and what OS you are running so it's hard to
>>>offer advice here.
>>>
>>>--
>>>Alex Bennée
>
>
>--
>Alex Bennée