Re: [Xen-devel] [PATCH for-4.5 v6 05/16] tools: Add vmware_port support

[Don Slutz <dslutz@xxxxxxxxxxx>]

On 09/25/14 07:24, Ian Campbell wrote:
> On Wed, 2014-09-24 at 12:31 -0400, Don Slutz wrote:
> > On 09/23/14 08:20, Ian Campbell wrote:
> > > On Mon, 2014-09-22 at 12:42 -0400, Don Slutz wrote:
[snip]

> > > And vmware_port is not ignored. 
> > > What I suggested was "if vmware_hw is non-zero then set vmware_port".
> > I am reading that as "set vmware_port if not specified".  To avoid
> > complexity, I am treating vmware_hw as a boolean.  Using this
> > I get the following table:
> >
> > _hw   _port
> >    0     0        Just like today
> >    1     0        Only cpuid leaves change -- very unlikey
> >    1     1        Full VMware mode
> >    0     1        VMware hyper call mode.
> >
> > Adding U for unspecified:
> >
> > _hw   _port
> >    U     U        ==> _hw=0 _port=0
> >    0     U        ==> _hw=0 _port=0
> >    1     U        The case in question.
> >    U     0        ==> _hw=0 _port=0
> >    U     1        What I was talking about.
> >    0     0        Just like today
> >    1     0        Only cpuid leaves change -- very unlikey
> >    1     1        Full VMware mode
> >    0     1        VMware hyper call mode.
> >
> > The problem here is that vmware_hw is not a boolean and there is
> > currently not a value that lets you know it has not been specified.
> The unspecified value is 0, surely? All of the rows with U under _hw can
> be ignored, I am talking only about _port being a defbool.
>
>    0     U        ==> _hw=0 _port=0
>    1     U        The case in question.
>
> => libxl should convert U to 1.
>
>    0     0        Just like today
>    1     0        Only cpuid leaves change -- very unlikey
>    1     1        Full VMware mode
>    0     1        VMware hyper call mode.
>
> All reasonable things to ask for explicitly, I think (I'm not so sure
> about the last one, might be an error?).
This is not an error as far as VMware says in "Mechanisms to determine
if software is running in a VMware virtual machine":

*Recommended code*

int Detect_VMware(void)
{
        if (cpuid_check())
                return 1;               // Success running under VMware.
        else if (dmi_check() && hypervisor_port_check())
                return 1;
        return 0;
}



If there is code that has issues with Xen in cpuid leaves and VMware port
"working", then yes this is a bad config to pick.

   -Don Slutz


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