On Tue, 2006-06-27 at 08:32 +1000, Robert Mueller wrote: > > - PAE (cast of dma_addr_t to unsigned long) issues. > > Can you explain a bit what this is about and what the effect is? It's just > that we've been using the driver (older version from the areca website) in a > PAE kernel on machines with 8G of memory and haven't had a problem yet > (running high IO load for several weeks) but this sounds like it > might/should cause corruption or crashing in this situation? It's these pieces: + pcmd->SCp.ptr = (char *)(unsigned long) dma_addr; + else if (pcmd->request_bufflen != 0) + pci_unmap_single(acb->pdev, + (dma_addr_t)(unsigned long)pcmd->SCp.ptr, + pcmd->request_bufflen, pcmd->sc_data_direction); On a PAE platform, dma_addr_t is u64 and unsigned long is u32, so any address > 4GB will be truncated by these operations. I think all this does is cause a slow leak of dma mappings, and on any kernel > 2.6.16 the leak should be even smaller, since we've severely restricted the use_sg == 0 case. It probably is only significant on x86_64 with the gart iommu enabled. James - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
