3.2 [aarch64] IOMMU issues

Performance issues, such as increased boot times, soft lockups, and crashes can occur on 64-bit Arm (aarch64) architecture that is running UEK R5 when the input–output memory management unit (IOMMU) feature is active. These issues have been observed on some Arm hardware using Mellanox CX-3 and CX-4 cards. However, note that similar issues could occur with different drivers on different hardware.

UEK R5 is configured to use swiotlb by default. To enable the use of the IOMMU feature, use iommu.passthrough=0 on the kernel command line. (Bug IDs 27687153, 27759954, 27812727, and 27862655)