[Qemu-devel] Can VMX provide real mode support?

[Qemu-devel] Can VMX provide real mode support?

[GaoYi]

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Hi Jan,

    Since the newest Intel-VT supports the guest OS under the real mode,
which was already supported in AMD-V, can the VMX in the latest KVM support
that case?

   Thanks,

Yi

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Re: [Qemu-devel] Can VMX provide real mode support?

[Jan Kiszka]

On 2012-03-21 13:38, GaoYi wrote:
> Hi Jan,
> 
>     Since the newest Intel-VT supports the guest OS under the real mode, which was already supported in AMD-V, can the VMX in the latest KVM support that case?

Yes, both with our without that "unrestricted guest" support (as Intel
called it), real mode will generally work. Without that CPU feature, I
think to recall that there were some limitations for big real mode, not
sure.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Re: [Qemu-devel] Can VMX provide real mode support?

[Avi Kivity]

On 03/21/2012 03:40 PM, Jan Kiszka wrote:
> On 2012-03-21 13:38, GaoYi wrote:
> > Hi Jan,
> > 
> >     Since the newest Intel-VT supports the guest OS under the real mode, which was already supported in AMD-V, can the VMX in the latest KVM support that case?
>
> Yes, both with our without that "unrestricted guest" support (as Intel
> called it), real mode will generally work. Without that CPU feature, I
> think to recall that there were some limitations for big real mode, not
> sure.
>

Yes, big real mode will not work without "unrestricted guest".  There
was some work to emulate it (module option emulate_invalid_guest_state),
but it is not complete.

-- 
error compiling committee.c: too many arguments to function

Re: [Qemu-devel] Can VMX provide real mode support?

[GaoYi]

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Hi,
   Thanks for your prompt response. So if the CPU supports the real
mode, the KVM can support the real mode guest and there is still work to be
done for CPU without real mode support, namely software emulation?

   Again

在 2012年3月21日 下午9:48，Avi Kivity <avi@redhat.com>写道：

> On 03/21/2012 03:40 PM, Jan Kiszka wrote:
> > On 2012-03-21 13:38, GaoYi wrote:
> > > Hi Jan,
> > >
> > >     Since the newest Intel-VT supports the guest OS under the real
> mode, which was already supported in AMD-V, can the VMX in the latest KVM
> support that case?
> >
> > Yes, both with our without that "unrestricted guest" support (as Intel
> > called it), real mode will generally work. Without that CPU feature, I
> > think to recall that there were some limitations for big real mode, not
> > sure.
> >
>
> Yes, big real mode will not work without "unrestricted guest".  There
> was some work to emulate it (module option emulate_invalid_guest_state),
> but it is not complete.
>
> --
> error compiling committee.c: too many arguments to function
>
>

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Re: [Qemu-devel] Can VMX provide real mode support?

[Luiz Capitulino]

On Wed, 21 Mar 2012 15:48:43 +0200
Avi Kivity <avi@redhat.com> wrote:

> On 03/21/2012 03:40 PM, Jan Kiszka wrote:
> > On 2012-03-21 13:38, GaoYi wrote:
> > > Hi Jan,
> > > 
> > >     Since the newest Intel-VT supports the guest OS under the real mode, which was already supported in AMD-V, can the VMX in the latest KVM support that case?
> >
> > Yes, both with our without that "unrestricted guest" support (as Intel
> > called it), real mode will generally work. Without that CPU feature, I
> > think to recall that there were some limitations for big real mode, not
> > sure.
> >
> 
> Yes, big real mode will not work without "unrestricted guest".  There
> was some work to emulate it (module option emulate_invalid_guest_state),
> but it is not complete.

Can you provide a pointer for this? series?

Re: [Qemu-devel] Can VMX provide real mode support?

[Avi Kivity]

On 03/23/2012 07:58 PM, Luiz Capitulino wrote:
> On Wed, 21 Mar 2012 15:48:43 +0200
> Avi Kivity <avi@redhat.com> wrote:
>
> > On 03/21/2012 03:40 PM, Jan Kiszka wrote:
> > > On 2012-03-21 13:38, GaoYi wrote:
> > > > Hi Jan,
> > > > 
> > > >     Since the newest Intel-VT supports the guest OS under the real mode, which was already supported in AMD-V, can the VMX in the latest KVM support that case?
> > >
> > > Yes, both with our without that "unrestricted guest" support (as Intel
> > > called it), real mode will generally work. Without that CPU feature, I
> > > think to recall that there were some limitations for big real mode, not
> > > sure.
> > >
> > 
> > Yes, big real mode will not work without "unrestricted guest".  There
> > was some work to emulate it (module option emulate_invalid_guest_state),
> > but it is not complete.
>
> Can you provide a pointer for this? series?

It's merged (look for emulate_invalid_guest_state in vmx.c), just
incomplete.

-- 
error compiling committee.c: too many arguments to function

Re: [Qemu-devel] Can VMX provide real mode support?

[GaoYi]

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So if the VT already supports unrestricted guest, KVM can then runs such
guest?

在 2012年3月25日 下午5:55，Avi Kivity <avi@redhat.com>写道：

>  On 03/23/2012 07:58 PM, Luiz Capitulino wrote:
> > On Wed, 21 Mar 2012 15:48:43 +0200
> > Avi Kivity <avi@redhat.com> wrote:
> >
> > > On 03/21/2012 03:40 PM, Jan Kiszka wrote:
> > > > On 2012-03-21 13:38, GaoYi wrote:
> > > > > Hi Jan,
> > > > >
> > > > >     Since the newest Intel-VT supports the guest OS under the real
> mode, which was already supported in AMD-V, can the VMX in the latest KVM
> support that case?
> > > >
> > > > Yes, both with our without that "unrestricted guest" support (as
> Intel
> > > > called it), real mode will generally work. Without that CPU feature,
> I
> > > > think to recall that there were some limitations for big real mode,
> not
> > > > sure.
> > > >
> > >
> > > Yes, big real mode will not work without "unrestricted guest".  There
> > > was some work to emulate it (module option
> emulate_invalid_guest_state),
> > > but it is not complete.
> >
> > Can you provide a pointer for this? series?
>
> It's merged (look for emulate_invalid_guest_state in vmx.c), just
> incomplete.
>
> --
> error compiling committee.c: too many arguments to function
>
>

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