Re: AW: Re: [Qemu-devel] VMport patch

[Anthony Liguori]

Alexander Graf wrote:
> On Jan 21, 2008, at 3:41 AM, Anthony Liguori wrote:
>
> > Mark Williamson wrote:
> > > > > I think it would be great to maintain compatibility with the 
> > > > > binary-only
> > > > > versions of the vm tools though.
> > > > But you're changing the semantics of the x86 instruction set.  You
> > > > potentially break a real operating system.  It also eliminates the
> > > > possibility of nesting with something like kqemu because you can't 
> > > > trap
> > > > all PIO operations.
> > >
> > > Maybe have a commandline flag, and have it switched off by default?  
> > > Or, even better, would be to detect valid vmware tools behaviour and 
> > > switch it on iff that happened; the default being to behave normally 
> > > for OSes that aren't running the VMware tools..
> >
> > There is no way to know for sure that it's vm-tools running.  You 
> > would have to make use of the cpu option to support it I reckon.
>
> I completely agree with the point of breaking x86 semantics is bad. 
> Yes, it is. What is the point in emulating the VMWare interface 
> though, if the only program actually requiring that interface does not 
> work, namely vmware tools, especially the windows version. So as far 
> as I know VMWare uses VMX to run 64-bit code on Intel as well, so 
> there has to be a way to forcefully break the checks.

vmmouse uses the vmport interface but runs in ring 0 under Linux so it's 
not an issue.  FWIW, the folks on open-vm-tools-devel have expressed an 
interest in moving to a different interface then their "backdoor" interface.

Regards,

Anthony Liguori

> Regards,
>
> Alex
>
> > Regards,
> >
> > Anthony Liguori
> >
> > > Cheers,
> > > Mark
> > >
> > >
> > > > Regards,
> > > >
> > > > Anthony Liguori
> > > >
> > > >
> > > > > Regards,
> > > > >
> > > > > Alex
> > > > >
> > > > > ----- Ursprüngliche Nachricht -----
> > > > > Von: Anthony Liguori <address@hidden>
> > > > > Gesendet: Sonntag, 20. Januar 2008 22:40
> > > > > An: address@hidden
> > > > > Betreff: Re: [Qemu-devel] VMport patch
> > > > >
> > > > > Filip Navara wrote:
> > > > >
> > > > > > Hello,
> > > > > >
> > > > > > the current version of QEMU emulates the VMware backdoor I/O port 
> > > > > > and
> > > > > > it works quite well. Unfortunately it doesn't emulate the VMware
> > > > > > behavior of ignoring the I/O permissions when accessing this special
> > > > > > port. The attached patch corrects it. It's important to ignore the
> > > > > > permissions, so that user mode VMware tools can communicate to the
> > > > > > backdoor. =
> > > > > I really dislike that VMware relies on this.  It's very hard to
> > > > > implement in kqemu or KVM.  I think it would be better to modify
> > > > > open-vm-tools than to modify QEMU.
> > > > >
> > > > > Regards,
> > > > >
> > > > > Anthony Liguori
> > > > >
> > > > >
> > > > > > Best regards,
> > > > > > Filip Navara