On Tue, Dec 28, 2010 at 08:00:12PM -0500, Jeff Garzik wrote: > (CC'd linux-ide, Joerg) > > On 12/28/2010 06:43 PM, Steffen Moser wrote: > > I've encountered a problem with my AMD 890FX based system > > and linux-2.6.35.10 (x86_64 platform). > > > > After activating the option "IOMMU" in the mainboard's BIOS > > setup, the onboard P-ATA controller "JMicron Technology Corp. > > JMB361 AHCI/IDE (rev 02)" puts itself back in the PIO mode. > > When loading the module, the kernel reports: > > > > pata_jmicron 0000:06:00.1: BMDMA: failed to set dma mask, \ > > falling back to PIO > [...] > > As soon as I deactivate IOMMU in BIOS setup, the P-ATA channel > > runs in the DMA mode again. The S-ATA controllers don't seem > > to be affected. > > > > My question is: Is this a known behavior? Are there any > > things I have to consider when activating IOMMU (which seems > > to be AMD-Vi) on an 890FX based system? Is it a problem of > > the chipset and/or the controller or is it related to a > > problem in the libata area? > > > > Some information about the affected system: > > > > - Mainboard: ASUS M4A89TD Pro/USB3 > > - BIOS version: 1101 (most recent version) > > - Chipset: AMD 890FX > > - Processor: AMD Phenom 1090T > > - Memory: 4 x 4 GB (Kingston KVR1333D3E9S/4G) > > - Distribution: openSUSE 11.3 > > - Kernel: 2.6.35.10 (from "kernel.org"), x86_64 > > > > This condition occurs when the PCI API cannot set the PCI device's DMA > mask to the 32-bit value > #define ATA_DMA_MASK 0xffffffffULL > > That is an unusual failure for such a modern system, which certainly can > handle 32-bit masks like that, one would think. Luckily I have exactly the same motherboard under my desk. It shows the same issue. The problem is that the PCI device of the PATA controler (4:00.1 in my case) is not described in the IVRS ACPI table. So the IOMMU driver does not feel responsible for it and the dma_supported() call on this device will fail. This also makes pci_set_dma_mask() fail on this device. So it comes down to a BIOS bug. I look into it to find a workaround. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
