There were some nasty bugs in the x86-64 code, including one race that
could cause random reboots, especially on Intel machines, with the NMI
watchdog.  This patch fixes them and also includes some harmless
cleanups.

Main fixes were for some buglets in the IOMMU code and the plugging of a
race in the exception stack handling.  Also disables an broken MCE on K8
explicitely.

Also finally the preempt compile issues are fixed.

 - Declare hpet interrupt separately in drivers/char/rtc.c
 - Fix rtc.h/hpet.h to not depend on interrupt.h
 - Finally include smp_lock.h in hardirq.h
 - Update defconfig
 - Export bad_dma_address
 - Merge with 2.6.5rc2
 - Never schedule on interrupt stacks.
 - Add option to force software iotlb (iommu=soft)
 - Add ifdefs to gsi patch to match i386 (Bjorn Helgaas)
 - Fix K8 GART TLB MCE workaround to actually work
 - Fix dwarf2 unwind table in SAVE_ARGS (Jim Houston)
 - Disable APIC on VIA/NVidia even with acpi=off (Gwenole Beauchesne)
 - Fix parsing bug in "apic" option (Gwenole Beauchesne)
 - Fix dma mask handling in pci_alloc_consistent
 - Make pci_alloc_consistent more robust in low memory situations.
 - Print version number in oopses (from i386)
 - ACPI GSI cleanup (Bjorn Helgaas)
 - Disable K8 GART TLB walk error MCE explicitely
 - Add support to disable individual MCEs in the various banks.