Re: [Xen-devel] [PATCH v2 06/13] x86/PMU: Add public xenpmu.h

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.09.13 at 15:25, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 09/25/2013 10:04 AM, Jan Beulich wrote:
>>>>> On 20.09.13 at 11:42, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
>>> +/* Intel PMU registers and structures */
>>> +#define XENPMU_CORE2_MAX_ARCH_PMCS     16
>>> +#define XENPMU_CORE2_MAX_FIXED_PMCS    4
>>> +struct core2_vpmu_context {
>>> +    uint64_t global_ctrl;
>>> +    uint64_t global_ovf_ctrl;
>>> +    uint64_t global_status;
>>> +    uint64_t global_ovf_status;
>>> +    uint64_t fixed_ctrl;
>>> +    uint64_t ds_area;
>>> +    uint64_t pebs_enable;
>>> +    uint64_t debugctl;
>>> +    uint64_t fix_counters[XENPMU_CORE2_MAX_FIXED_PMCS];
>>> +    struct {
>>> +        uint64_t counter;
>>> +        uint64_t control;
>>> +    } arch_msr_pair[XENPMU_CORE2_MAX_ARCH_PMCS];
>>> +};
>> I realize that using embedded arrays in both AMD and Intel
>> structures makes things easier to implement, but it reduces
>> forward compatibility. I'd therefore prefer those to be made
>> handles.
> 
> (I missed this comment earlier).
> 
> This is not done because it's easier but because I need to keep the
> structure in a shared page.

Then a more dynamic layout (with just the array base offset in the
page specified in the structure) would still be preferable as being
more extensible.

Jan


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