On Thu, Dec 08, 2005 at 09:17:15AM +0200, Or Gerlitz wrote: > Roland Dreier wrote: > >The right way to use the MR from get_dma_mr() is to use "bus > >addresses" from the DMA mapping API. For highmem, the right way to > >get those addresses is with dma_map_sg() or dma_map_page(). > > Looking on the kernel x86_64 code, both dma_map_sg and dma_map_page seem > to assume that the page is already mapped, since they call > page_address(page).
x86_64 doesn't have highmem, so page_address(page) is valid on every page. > Specifically is it safe in a SCSI LLD (eg SRP and iSER which is among > other things such) to call dma_map_sg on a SG which comes with a SCSI yes, this is definitly safe. > command, so the SCSI Mid-Layer always makes sure the pages are mapped? no, it doesn't. in fact pages don't need to be mapped at all for dma normally. _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
