Re: [PATCH 2/2] expert_mode: Add a new configuration option for expert users.

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

On 17/07/13 11:56, Ian Jackson wrote:
> Ian Campbell writes ("Re: [Xen-devel] [PATCH 2/2] expert_mode: Add a new configuration option for expert users."):
>> On Fri, 2013-07-12 at 14:08 -0400, Konrad Rzeszutek Wilk wrote:
>>> This could also be called 'seatbelt' option.
>>>
>>> libxl has a variety of checks where it will fail out an operation
>>> unless the user has provided an --force (or --ignore) parameter.
>>> Currently one such check is for the 'vcpu-set' command which
>>> will error out if the count of virtual cpus is greater than the
>>> physical cpus. This parameter will ignore such checks and allow
>>> the user to do the operations without the need for override flags.
>> Does this overlap  somewhat with various commands which individually
>> take a -f(orce) option?
> Clearly it should disable all of those -f's too.
>
>>> +=item B<expert_mode=BOOLEAN>
>>> +
>>> +Do not act on host performed checks that might lead to performance
>>> +degradations. Currently checks are made for following operations:
>>> + - C<vcpu-set> - if the number of VCPUs set for a guest is higher than the
>>> +   physical count the operation will error out.
> I don't think this is a very coherent specification.  Surely it should
> override "all -f options" or something similar.

I think that makes sense for some but not all.  For example, for "xl 
shutdown", -f means "send an ACPI event if no PV drivers are detected".  
I don't think we'd want to change that behavior with such a switch.  
(Arguably -f was the wrong option to use for that in the first place, 
but it's a bit late for that now.)

  -George.