CONFIG_SWIOTLB (not configurable)

modulename: dma-swiotlb.ko

and/or

swiotlb.ko

and/or

pci-swiotlb.ko

configname: CONFIG_SWIOTLB

Linux Kernel Configuration
└─>Processor type and features
└─>SWIOTLB
In linux kernel since version 2.6.12  
Support for software bounce buffers used on x86-64 systems
which don't have a hardware IOMMU. Using this PCI devices
which can only access 32-bits of memory can be used on systems
with more than 3 GB of memory.
If unsure, say Y.