Re: [Xen-devel] [PATCH] x86/numa: Adjust datatypes for node and pxm

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.02.15 at 15:42, <boris.ostrovsky@xxxxxxxxxx> wrote:
> On 02/23/2015 04:57 AM, Jan Beulich wrote:
>>>>> On 21.02.15 at 19:14, <boris.ostrovsky@xxxxxxxxxx> wrote:
>>> --- a/xen/arch/x86/srat.c
>>> +++ b/xen/arch/x86/srat.c
>>> @@ -21,44 +21,55 @@
>>>   #include <asm/e820.h>
>>>   #include <asm/page.h>
>>>   
>>> +#define MAX_PXM   255
>> Perhaps better (MAX_NUMNODES - 1) than a literal number? Or
>> even do away with it altogether, use MAX_NUMNODES - 1 in the
>> array definition and ARRAY_SIZE() elsewhere?
> 
> I am not sure we can do this: PXMs are not guaranteed to be zero-based.
> 
> And, in fact, the way we map PXMs to nodes is not quite right because of 
> this --- it just so happens that PXMs are usually under 255 (and 
> zero-based) and we can use them as index to 255-sized array. IIRC the 
> spec defines them as 32-bit values.

Ah, yes, you're right. We may need to allocate the array dynamically
as soon as we run into a system with large PXMs.

Jan


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