Re: [Xen-devel] Other PCI devices to mark mark as read-only for dom0

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.06.12 at 14:06, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> On 22/06/12 12:23, Jan Beulich wrote:
>>>>> On 22.06.12 at 12:08, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>>> On 22/06/12 10:43, Jan Beulich wrote:
>>>>>>> On 22.06.12 at 11:04, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
>>>>> Following Jan's infrastructure to mark certain PCI devices as read only,
>>>>> I think it wise to now consider what other PCI devices should really be
>>>>> read only to dom0.
>>>>>
>>>>> My preliminary thoughts include:
>>>>>
>>>>> * PCI serial devices which Xen is configured to use
>>>> But only if they're single-function.
>>> Why only single function?  Should Xen not turn all the functions it is
>>> using to read-only ?
>> Because, just like for normal, non-PCI based serial ones, ports
>> that Xen doesn't use should remain usable by Dom0. For
>> example, I have a PCI card with two serial and one parallel
>> ports, so with Xen using one serial port for itself, there's no
>> reason not to allow Dom0 to use the other or the parallel one.
> 
> I apologize.  I originally used the term 'device' when I intended to use
> 'function', so I think we are arguing for the same point.

And I understood you meaning so - from a PCI terminology pov.
Multi-function here, however, means multiple serial/parallel ports
within a single PCI function (PCI_CLASS_COMMUNICATION_MULTISERIAL
or PCI_CLASS_COMMUNICATION_OTHER). Hence we shouldn't hide a
full S:B:D.F just because we use some portion of it.

Jan


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