Without these changes an x86-64 NUMA kernel won't boot in many
configurations.

The main change is the improved IOMMU code which supports merging of
mappings and has various bugfixes.

 - Update defconfig
 - Use argument ptregs in 32bit elf_core_copy_task_fpregs
 - Harden aperture fixup code: read aperture from the AGP bridge if needed,
   better error checking.
 - Support nmi_watchdog=panic to panic on watchdog trigger
 - IOMMU: Support panic on IOMMU overflow (iommu=panic)
 - IOMMU: Force SAC for mappings >40bits when iommu=force is active
   (this can potentially give better performance)
 - IOMMU: Cache northbridges for faster TLB flush
 - IOMMU: Fix SMP race in TLB flush
 - IOMMU: Merge pci_alloc_consistent and pci_map_single
 - IOMMU: Clean up leak tracing
 - IOMMU: Rewrite pci_map_sg, support merging of mappings
   On overflow fall back to piece-by-piece mapping.
 - IOMMU: Tell block layer to assume merging when iommu force is active
   (this gives better performance with MTP fusion, drawback is that the
   overflow/fragmentation handling of the IOMMU area is still a big
   dubious with that)
 - Fix/clean up per cpu data
 - Add 64bit clean time(2)
 - Export cpu_callout_map for IPv6
 - Handle nodes with no own memory in NUMA discovery.
   This fixes boot on various newer Opteron motherboards where the memory
   is only connected to a single CPU.
 - Fix fallback path for failed NUMA discovery. numnodes has to be reset.
 - Check for enabled nodes in NUMA discovery (Eric Biederman)
 - Remove NUMA emunodes support. Has badly bitrotted.
 - Add __clear_bit_string for IOMMU code
 - Add new 32bit system calls to ia32_unistd.h
 - Remove duplicate default_do_nmi prototype
 - Make PCI_DMA_BUS_IS_PHYS dependent on no_iommu
 - Fix padding length of siginfo_t to match glibc
 - More pci direct access functions.