Re: [PATCH 18 of 38] x86: unify pci iommu setup and allow swiotlbto compile for 32 bit

[FUJITA Tomonori]

On Thu, 13 Nov 2008 11:10:16 -0800
Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:

> swiotlb on 32 bit will be used by Xen domain 0 support.

If you want swiotlb on 32 bit, you need more modifications, I think.

For example, the following code assumes that the mask needs to be
64 bits.

static void *
map_single(struct device *hwdev, char *buffer, size_t size, int dir)
{
	unsigned long flags;
	char *dma_addr;
	unsigned int nslots, stride, index, wrap;
	int i;
	unsigned long start_dma_addr;
	unsigned long mask;
	unsigned long offset_slots;
	unsigned long max_slots;

	mask = dma_get_seg_boundary(hwdev);
	start_dma_addr = virt_to_bus(io_tlb_start) & mask;

	offset_slots = ALIGN(start_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
	max_slots = mask + 1
		    ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT
		    : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT);

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