Re: virt_to_page/pci_map_page vs. pci_map_single

From: Jes Sorensen
Date: Tue Nov 04 2003 - 04:51:43 EST

>>>>> "James" == James Bottomley <James.Bottomley@xxxxxxxxxxxx> writes:

James> Erm, I don't think so. pci_map_single() covers a different use
James> case from pci_map_page().

James> The thing pci_map_single() can do that pci_map_page() can't is
James> cope with contiguous regions greater than PAGE_SIZE in length
James> (which you get either from kmalloc() or __get_free_pages()).
James> This feature is used in the SCSI layer for instance.

The question is whether that should be allowed in the first place. Some
IOMMU's will have to map it page-by-page anyway. However if it is to
remain a valid use then I don't see why pci_map_page() shouldn't be
able to handle it under the same conditions by passing it a
size > PAGE_SIZE.


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