[Intel IOMMU] Support for Intel Virtualization Technology for Directed I/O

Hi,

Pleased to announce support for Intel(R) Virtualization Technology for 
Directed I/O use as an IOMMU in Linux.

This is a series of patches to support the same. 

A brief description of the patches follows.

1. Support for ACPI framework to parse and work with DMA Remapping Tables.
2. Add support for PCI infrastructure to search parent relationships.
3. Hardware support for providing DMA remapping support for Intel Chipsets.
4. Supporting Zero Length Reads on DMAR's not able to support ZLR.
5. Graphics driver workarounds to provide unity map since they dont use dma api.
6. Updates to Documentation area for startup options and some basics.
7. Workaround to provide unity map for ISA bridge device to enable floppy disk.
8. Ability to preserve some mappings for devices not able to address entire 
   range.

Please help review and provide feedback.

Cheers,
Ashok Raj & Shaohua Li