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

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

[tugouxp]

hi folks:
     did the qemu can emulate the whole system(such as ubuntu) with the processor that without support the "virtulization and kvm"?


thanks for your kindly support.

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

[Alex Bennée]

tugouxp <13824125580@163.com> writes:

> hi folks:
>      did the qemu can emulate the whole system(such as ubuntu) with
>      the processor that without support the "virtulization and kvm"?

I don't quite follow your question. However if you are asking about the
cross-architecture emulation (usually called TCG) the features of the
processor depend on how complete the front-end is.

So you can for example boot an aarch64 system under emulation that can
itself run KVM guests (because we implement EL0/1/2/3). However you
the system can't currently use VHE extensions because the support for
that has yet to be added.

What is your use-case?

--
Alex Bennée

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

[tugouxp]

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.


thanks for your support.!









At 2018-12-20 20:31:09, "Alex Bennée" <alex.bennee@linaro.org> wrote:
>
>tugouxp <13824125580@163.com> writes:
>
>> hi folks:
>>      did the qemu can emulate the whole system(such as ubuntu) with
>>      the processor that without support the "virtulization and kvm"?
>
>I don't quite follow your question. However if you are asking about the
>cross-architecture emulation (usually called TCG) the features of the
>processor depend on how complete the front-end is.
>
>So you can for example boot an aarch64 system under emulation that can
>itself run KVM guests (because we implement EL0/1/2/3). However you
>the system can't currently use VHE extensions because the support for
>that has yet to be added.
>
>What is your use-case?
>
>--
>Alex Bennée

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

[Alex Bennée]

tugouxp <13824125580@163.com> 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

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

[tugouxp]

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?



thanks very much!









At 2018-12-21 17:01:02, "Alex Bennée" <alex.bennee@linaro.org> wrote:
>
>tugouxp <13824125580@163.com> 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

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

[Li Zhijian]

On 12/21/18 19:40, tugouxp wrote:
> 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.

IIUC，
"operation system" often means a software but QEMU usually emulates hardwares, including cpus, memory, NIC, etc.
Please know that QEMU born earlier than KVM, so QEMU can work well without KVM.

Thanks


> so from the answer you give to me, it is feasible, right?
>
>
>
> thanks very much!
>
>
>
>
>
>
>
>
>
> At 2018-12-21 17:01:02, "Alex Bennée" <alex.bennee@linaro.org> wrote:
>> tugouxp <13824125580@163.com> 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
>
-- 
Best regards.
Li Zhijian (8528)

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

[Alex Bennée]

tugouxp <13824125580@163.com> 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" <alex.bennee@linaro.org> wrote:
>>
>>tugouxp <13824125580@163.com> 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

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" <alex.bennee@linaro.org> wrote:
>
>tugouxp <13824125580@163.com> 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" <alex.bennee@linaro.org> wrote:
>>>
>>>tugouxp <13824125580@163.com> 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