Re: [Xen-devel] [PATCH 01/11] xen/arm: use dma-noncoherent.h calls for xen-swiotlb cache maintainance

[Christoph Hellwig]

On Mon, Aug 19, 2019 at 12:45:17PM +0100, Julien Grall wrote:
> On 8/16/19 2:00 PM, Christoph Hellwig wrote:
>> +static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
>> +	     dma_addr_t dev_addr, unsigned long offset, size_t size,
>> +	     enum dma_data_direction dir, unsigned long attrs)
>> +{
>> +	unsigned long page_pfn = page_to_xen_pfn(page);
>> +	unsigned long dev_pfn = XEN_PFN_DOWN(dev_addr);
>> +	unsigned long compound_pages =
>> +		(1<<compound_order(page)) * XEN_PFN_PER_PAGE;
>> +	bool local = (page_pfn <= dev_pfn) &&
>> +		(dev_pfn - page_pfn < compound_pages);
>> +
>
> The Arm version as a comment here. Could we retain it?

I've added it in this patch, altough the rewrites later on mean it will
go away in favour of a new comment elsewhere anyway.