[PATCH 5/5] RISC-V: Implement sparsemem

Logan Gunthorpe logang at deltatee.com
Thu Oct 11 09:24:33 PDT 2018



On 2018-10-11 7:37 a.m., Christoph Hellwig wrote:
>> +/*
>> + * Log2 of the upper bound of the size of a struct page. Used for sizing
>> + * the vmemmap region only, does not affect actual memory footprint.
>> + * We don't use sizeof(struct page) directly since taking its size here
>> + * requires its definition to be available at this point in the inclusion
>> + * chain, and it may not be a power of 2 in the first place.
>> + */
>> +#define STRUCT_PAGE_MAX_SHIFT	6
> 
> I know this is copied from arm64, but wouldn't this be a good time
> to move this next to the struct page defintion?
> 
> Also this:
> 
> arch/arm64/mm/init.c:   BUILD_BUG_ON(sizeof(struct page) > (1 << STRUCT_PAGE_MAX_SHIFT));
> 
> should move to comment code (or would have to be duplicated for riscv)

Makes sense. Where is a good place for the BUILD_BUG_ON in common code?

I've queued up changes for your other feedback.

Thanks,

Logan



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