Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Disable interrupts when calling into SAL for PCI configuration
cycles. This serves 2 purposes:
1. It prevents preemption and CPU migration while running SAL code.
2. It reduces the chance of stack overflows: we're supposed to enter
SAL with at least 16KB of either memory- or register stack space,
which we can't do without switching to a different stack.

In pci_cfgregread() and pci_cfgregwrite(), validate the arguments and check
that the alignment matches the width of the read or write.

The encoding for the bus being passed to SAL was completely wrong.

Start hooking up devices.