Re: [PATCH v7 2/5] sysctl: Add sysctl interface for querying PCI topology

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 21/04/15 13:56, Boris Ostrovsky wrote:
>
> On 04/21/2015 03:01 AM, Jan Beulich wrote:
>>>>> On 17.04.15 at 18:59, <boris.ostrovsky@oracle.com> wrote:
>>> Changes in v7:
>>> * Break from the loop when -ENODEV is encountered
>> This seems pretty inefficient for the caller. Returning a "bad"
>> identifier other than XEN_INVALID_NODE_ID would seem better
>> to me.
>
> That would mean that there is really no reason to return -ENODEV,
> which I thought you wanted to see. In that case (i.e. if no error
> needs to be returned) yes, a new token would make things simpler.
>
>>
>>> --- a/docs/misc/xsm-flask.txt
>>> +++ b/docs/misc/xsm-flask.txt
>>> @@ -121,6 +121,7 @@ __HYPERVISOR_sysctl (xen/include/public/sysctl.h)
>>>    * XEN_SYSCTL_cpupool_op
>>>    * XEN_SYSCTL_scheduler_op
>>>    * XEN_SYSCTL_coverage_op
>>> + * XEN_SYSCTL_pcitopoinfo
>> No additions to this list are permitted. Either the new sub-op is
>> disaggregation safe (which it looks to be), or it can't be accepted.
>
> True, it *is* safe, but why then cputopoinfo and numainfo are in this
> list? They look to be safe as well.

This list includes "not yet audited".  It is quite likely that some
entries in the list are safe.

fwiw, neither cputopo nor numainfo are currently safe for very large
systems.

~Andrew