Re: [PATCH] pm : provide CC7/PC2 residency

[Christoph Egger <Christoph.Egger@amd.com>]

On 11/02/11 10:48, Zhang, Yang Z wrote:
>> From: Jan Beulich [mailto:JBeulich@suse.com]
>>>>> On 25.10.11 at 15:34, "Zhang, Yang Z"<yang.z.zhang@intel.com>  wrote:
>>> --- a/xen/include/public/sysctl.h       Mon Oct 24 18:01:07 2011 +0100
>>> +++ b/xen/include/public/sysctl.h       Fri Oct 28 21:33:07 2011 +0800
>>> @@ -225,11 +225,13 @@
>>>       uint64_aligned_t idle_time;                 /* idle time from boot */
>>>       XEN_GUEST_HANDLE_64(uint64) triggers;    /* Cx trigger counts */
>>>       XEN_GUEST_HANDLE_64(uint64) residencies; /* Cx residencies */
>>> +    uint64_aligned_t pc2;
>>>       uint64_aligned_t pc3;
>>>       uint64_aligned_t pc6;
>>>       uint64_aligned_t pc7;
>>>       uint64_aligned_t cc3;
>>>       uint64_aligned_t cc6;
>>> +    uint64_aligned_t cc7;
>>>   };
>>>
>>>   struct xen_sysctl_get_pmstat {
>>
>> Structure layout changes like this should be accompanied by a bump of
>> XEN_SYSCTL_INTERFACE_VERSION - is there any reason not to do so in this case?
> Can you explain what's the problem? Are you mean new xen with old tools will have problem or anything else?

The problem is API/ABI backward-compatibility.

Christoph

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