On Wed, Jun 01, 2005 at 01:48:33PM -0700, Roland Dreier wrote: > Here's a patch that allows mthca to break up registration of giant > userspace MRs into multiple firmware commands. The net effect of this > is that there should no longer be any limit (beyond physical memory) > on the size of MRs that userspace can register.
There is a limit on some platforms: IO Virtual Address (IOVA) space I'm not worried about it on ia64 platforms since they mostly direct map for 64-bit devices. Either they have no IOMMU or 64-bit devices are allowed to bypass the IOMMU. parisc only has 1GB per IOMMU (and several can be in a system). Roland also once mentioned a PPC box that also forces everything through the IOMMU. The problem is sga_dma_map* functions do not return an error. One needs to call dma_mapping_error() to verify the IO address returned was valid. This is a relatively new interface so I wouldn't expect that many driver writers are not aware of it. Most don't need to be aware of it since they don't attempt to map GBs of physical memory at a time. grant _______________________________________________ openib-general mailing list [email protected] http://openib.org/mailman/listinfo/openib-general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
