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

[Anthony Liguori <anthony@codemonkey.ws>]

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 <anthony@codemonkey.ws>
>>>>> Gesendet: Sonntag, 20. Januar 2008 22:40
>>>>> An: qemu-devel@nongnu.org
>>>>> 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
>>>>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>
>
>