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

[Don Slutz <dslutz@verizon.com>]

On 09/23/14 08:20, Ian Campbell wrote:
> On Mon, 2014-09-22 at 12:42 -0400, Don Slutz wrote:
>>> The latter would allow moving to buildinfo.u.hvm, which would be nicer
>>> from the libxl PoV, I think.
>> I could not find "buildinfo.u.hvm":
>>
>>
>> dcs-xen-54:~/xen>git grep buildinfo.u.hvm
>> dcs-xen-54:~/xen>
>>
>>
>> So unable to comment.
> It's in the idl, next to createinfo.

I take that to mean:


libxl_domain_config = Struct("domain_config", [
     ("c_info", libxl_domain_create_info),
     ("b_info", libxl_domain_build_info),
...

I.E.

b_info->u.hvm


>>> If yes then I still think you would want to set the default based on
>>> vmware-hw, wouldn't you?
>> I guess so since this is a BOOLEAN.
> defbool I hope.

Yes.

>>    Currently I do not know of a way to
>> say "set vmware_hw to 7
>> if vmware_port is true and vmware_hw is not specified".
> That's an error case, isn't it? Or at least a vmware_port is ignored
> case.

Nope.  But I will agree that I have not done a lot with 3 (at least)
state booleans.  The 3 states being true, false, and not specified.

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.

So I think it is just more confusing to have vmware_hw change
the default of vmware_port but the inverse is not true.

    -Don Slutz

>>    Which would be
>> the inverse.  I lean to
>> not having the default of vmware_port based on vmware_hw.