Add ipf.
Update to match reality more closely.
add files related to the new rc world order.
Bracket kernel structs with #ifdef _KERNEL so that bootblocks will once
again build.
Sync to 4.4BSD-Lite2; really just the SCCS ID, because we don't have vfslist.c in our mount sources.
s/soft error/soft error (corrected)/, to avoid confusion.
RFC 1597 has been obsoleted by RFC 1918.
Define top-level MIB node for DDB (CTL_DDB) and DDB MIB identifiers.
Define db_onpanic variable; if non-zero, the DDB will be entered when
the kernel panics.  It may be initialized to 0 with the kernel option
"DDB_ONPANIC=0", and is patchable.  It may be changed at run-time
from within the DDB (as a DDB variable) or via the ddb.onpanic sysctl
node.

Export all DDB built-in variables via sysctl.
Grok CTL_DDB.
Only call Debugger() on panic if "db_onpanic" is set.
Grok and document CTL_DDB.
Document CTL_DDB MIB nodes.
Document "onpanic" built-in variable.
fix typo
Document DDB_ONPANIC.
Add missing "\".
Sync to 4.4BSD-Lite2
Add CACHE40_ON, for locore
Sync with current 040-related development:

 - Combine initenv() and getenvvars().
 - Hardwire some PowerBook internal video addresses, from Takashi Hamada.
 - When printing out the machine model/CPU, use the new cputype variable
   instead of the Booter's PROCESSOR environment variable.
 - Use new ptest040() function code argument (though for now, the MMU is
   disabled on the 040).
 - Revert previous change in get_physical() that seems to have broken
   some machines; use an ADD instead of an OR when determining the PA.
 - Some (very minor) style cleanup of asm code.