RE: [Xen-devel] about vmxassist

["Kamala Narasimhan" <Kamala.Narasimhan@xxxxxxxxxx>]

> Hi All,
> Can someone clarify this for me : when using vmxassist , is BIOS
> running in virtual8086 mode ? 

        When using vmxassist, the ROMBIOS/VGABIOS code executed within a
HVM (VMX) domain runs in VM8086 mode.  Instructions unsupported in this
mode generate a GPF when executed which vmxassist catches and attempts
to emulate.  I would suggest referring to tools/firmware/README for
further information.

> And if do not use it , BIOS will run in
> real-address mode , right ?

        Intel VT-x doesn't provide real mode support for HVM guests.  If
you don't use vmxassist, you could use full real-mode emulation.  In
fact, this is the default with the latest xen-unstable which doesn't
support vmxassist anymore.

Kamala

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