CONFIG_CALGARY_IOMMU is not available for thedefaultarchitecture x86.
Result is shown for architecture 64BIT

IBM Calgary IOMMU support

modulename: pci-calgary_64.ko

configname: CONFIG_CALGARY_IOMMU

Linux Kernel Configuration
└─>Processor type and features
└─>IBM Calgary IOMMU support
In linux kernel since version 2.6.18 (release Date: 2006-09-19)  
Support for hardware IOMMUs in IBM's xSeries x366 and x460
systems. Needed to run systems with more than 3GB of memory
properly with 32-bit PCI devices that do not support DAC
(Double Address Cycle). Calgary also supports bus level
isolation, where all DMAs pass through the IOMMU. This
prevents them from going anywhere except their intended
destination. This catches hard-to-find kernel bugs and
mis-behaving drivers and devices that do not use the DMA-API
properly to set up their DMA buffers. The IOMMU can be
turned off at boot time with the iommu=off parameter.
Normally the kernel will make the right choice by itself.
If unsure, say Y.