Re: [PATCH v4 1/6] libnvdimm/namespace: Make namespace size validation arch dependent

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

On 1/24/20 11:27 AM, Dan Williams wrote:
> On Mon, Jan 20, 2020 at 6:08 AM Aneesh Kumar K.V
>

....

>>
>> +unsigned long arch_namespace_map_size(void)
>> +{
>> +       return PAGE_SIZE;
>> +}
>> +EXPORT_SYMBOL_GPL(arch_namespace_map_size);
>> +
>> +
>>   static void __cpa_flush_all(void *arg)
>>   {
>>          unsigned long cache = (unsigned long)arg;
>> diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h
>> index 9df091bd30ba..a3476dbd2656 100644
>> --- a/include/linux/libnvdimm.h
>> +++ b/include/linux/libnvdimm.h
>> @@ -284,4 +284,5 @@ static inline void arch_invalidate_pmem(void *addr, size_t size)
>>   }
>>   #endif
>>
>> +unsigned long arch_namespace_map_size(void);
> 
> This property is more generic than the nvdimm namespace mapping size,
> it's more the fundamental remap granularity that the architecture
> supports. So I would expect this to be defined in core header files.
> Something like:
> 
> diff --git a/include/linux/io.h b/include/linux/io.h
> index a59834bc0a11..58b3b2091dbb 100644
> --- a/include/linux/io.h
> +++ b/include/linux/io.h
> @@ -155,6 +155,13 @@ enum {
>   void *memremap(resource_size_t offset, size_t size, unsigned long flags);
>   void memunmap(void *addr);
> 
> +#ifndef memremap_min_align
> +static inline unsigned int memremap_min_align(void)
> +{
> +       return PAGE_SIZE;
> +}
> +#endif
> +


Should that be memremap_pages_min_align()?

>   /*
>    * On x86 PAT systems we have memory tracking that keeps track of
>    * the allowed mappings on memory ranges. This tracking works for
> 
> ...and then have a definition is asm/io.h like this:
> 
> unsigned int memremap_min_align(void);
> #define memremap_min_align memremap_min_align
> 
> That way only architectures that want to opt out of the default need
> to define something in their local header.
> 

-aneesh
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