Messages in this thread | | | Date | Mon, 3 Nov 2003 07:52:59 -0500 | From | Jamie Wellnitz <> | Subject | Re: virt_to_page/pci_map_page vs. pci_map_single |
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On Mon, Nov 03, 2003 at 03:10:46AM -0500, Jes Sorensen wrote: > >>>>> "Jamie" == Jamie Wellnitz <Jamie.Wellnitz@emulex.com> writes: > > Jamie> page = virt_to_page(buffer); offset = ((unsigned long)buffer & > Jamie> ~PAGE_MASK); busaddr = pci_map_page(pci_dev, page, offset, len, > Jamie> direction); > > Jamie> How is this preferable to: > > Jamie> pci_map_single( pci_dev, buffer, len, direction); > > Jamie> pci_map_single can't handle highmem pages (because they don't > Jamie> have a kernel virtual address) but doesn't virt_to_page suffer > Jamie> from the same limitation? Is there some benefit on > Jamie> architectures that don't have highmem? > > virt_to_page() can handle any page in the standard kernel region
What is the "standard kernel region"? ZONE_NORMAL?
> including pages that are physically in 64-bit space if the > architecture requires it. It doesn't handle vmalloc pages etc. but > one shouldn't try and dynamically map vmalloc pages at > random. pci_map_page() can handle all memory in the system though as > every page that can be mapped has a struct page * entry. > > pci_map_page() is the correct API to use, pci_map_single() is > deprecated.
Are you talking about 2.4 or 2.6 or both?
The Document/DMA-mapping.txt in 2.6.0-test9 says "To map a single region, you do:" and then shows pci_map_single. Is DMA-mapping.txt in need of patching?
> > Cheers, > Jes
Thanks, Jamie Jamie.Wellnitz@emulex.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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