Re: RFC: Automatically making a PCI device assignable in the config file

[George Dunlap <george.dunlap@eu.citrix.com>]

On 12/07/13 17:02, Konrad Rzeszutek Wilk wrote:
> On Fri, Jul 12, 2013 at 04:09:29PM +0100, George Dunlap wrote:
>> On 12/07/13 16:01, Konrad Rzeszutek Wilk wrote:
>>> On Fri, Jul 12, 2013 at 03:43:32PM +0100, Ian Jackson wrote:
>>>> Konrad Rzeszutek Wilk writes ("Re: [Xen-devel] RFC: Automatically making a PCI device assignable in the config file"):
>>>>> On Fri, Jul 12, 2013 at 02:10:41PM +0100, Ian Jackson wrote:
>>>>>> I think at the very least there should be the ability to have it as a
>>>>>> global config option.
>>>>> Like the seatbelt option or perhaps a better name 'expert' in the /etc/xl.conf?
>>>> I was thinking "default.pci.seize" or something.
>>> Why not combine this with the other - the one where you can call
>>> 'xl vpcu-set <guest> <huge number of VCPUs>' where the number of
>>> VCPUs is greater than PCPUs. And if the 'expert' option is turned
>>> on it will let you. If it is not, it will notify you about this
>>> being a bad idea.
>> ...because you may want to have one and not the other?
> Seatbelts are seatbelts. They have many parts - but nonethless
> at the end of the day you describe them by just one word.
>
> I am not a big fan of many knobs - even thought I did work at some
> point for IBM which was known for its knob-for-everything products.

Well remember that my main concern here is with the *changing* of 
behavior, not the *existence* of behavior.  (i.e., xl pci-assignable-add 
already behaves in the way in which xl pci-attach would behave with the 
seatbelt off).  If we had already had a single "expert" option in 
xl.conf, then we would be in nearly the same situation -- add xl 
pci-attach to the "expert" option and have it change from safe to unsafe 
without any warning, or add yet another parameter.

  -George