of the `machdep.acpi_root' sysctl. This is required on ia64
because the root pointer hardly ever, if at all, lives in the
first MB of memory and also because scanning the first MB of
memory can cause machine checks.
This provides a save and reliable way for ACPI tools to work
with the tables if ACPI support is present in the kernel. On
ia64 ACPI is non-optional.
and attach routines have succeeded so that if they fail we can still use
the PnP BIOS to find ISA on-board devices. The fact that we do this here
is gross but fixing it properly involves a lot more work.
