[+cc Konrad, Joerg, iommu list] On Fri, Oct 02, 2015 at 04:20:16PM +0200, Christian Melki wrote: > I discovered a strange error on my machine. 32-bit PAE 4.2.0 without > IOMMU code (yeah, I know). > When writing to an ext4 filesystem on a USB disk my kernel would hang > and not return control to userspace. It would spew kernel messages to > syslog as fast as it could without giving userspace any time, ie "hang" > as far as a user sees it. The device itself is ok and the filesystem is > clean. > I get messages like this, millions of them. > > Oct 2 14:33:06 voodoochild kernel: [ 223.287447] nommu_map_sg: > overflow 25dcac000+1024 of device mask ffffffff > Oct 2 14:33:06 voodoochild kernel: [ 223.287448] nommu_map_sg: > overflow 25dcac000+1024 of device mask ffffffff > Oct 2 14:33:06 voodoochild kernel: [ 223.287449] nommu_map_sg: > overflow 25dcac000+1024 of device mask ffffffff > > I disovered that SWIOTLB was not on. It is only provided for 64-bit > machines where it is default. On 32-bit SWIOTLB seems disabled > unless you are running with some IOMMU/AGPGART code. > > But what about 32-bit PAE? Would that not qualify for SWIOTLB without IOMMU? > > I am a novice in this area. Maybe this is a Kconfig "bug" for us > that like to hang ourselves with CONFIG_* rope? :) I'd like to think > that SWIOTLB should be default for 32-bit PAE too? > > Best regards, > Christian > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
