Remove support for running 32-bit kernels on 64-bit hardware.

This was useful in bring up. However, it causes more issues than the
support is worth (64-bit atomics being chief among them).

Discussed on: freebsd-mips@
Differential Revision: https://reviews.freebsd.org/D18543

UPDATING

@@ -31,6 +31,15 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 13.x IS SLOW:
 	disable the most expensive debugging functionality run
 	"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20181215:
+	The XLP config has been removed. We can't support 64-bit atomics in this
+	kernel because it is running in 32-bit mode. XLP users must transition
+	to running a 64-bit kernel (XLP64 or XLPN32).
+
+20181215:
+	The mips GXEMUL support has been removed from FreeBSD. MALTA* + qemu is
+	the preferred emulator today and we don't need two different ones.
+
 20181215:
 	The old sibyte / swarm / Broadcom BCM1250 support has been
 	removed from the mips port.

sys/mips/conf/XLP

@@ -1,28 +0,0 @@
-# XLP -- Generic kernel configuration file for FreeBSD/mips
-#
-# For more information on this file, please read the handbook section on
-# Kernel Configuration Files:
-#
-#    https://www.FreeBSD.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig-config.html
-#
-# The handbook is also available locally in /usr/share/doc/handbook
-# if you've installed the doc distribution, otherwise always see the
-# FreeBSD World Wide Web server (https://www.FreeBSD.org/) for the
-# latest information.
-#
-# An exhaustive list of options and more detailed explanations of the
-# device lines is also present in the ../../conf/NOTES and NOTES files. 
-# If you are in doubt as to the purpose or necessity of a line, check first 
-# in NOTES.
-#
-# $FreeBSD$
-
-machine 	mips mips
-ident           XLP
-
-makeoptions	KERNLOADADDR=0x80100000
-
-include		"std.XLP"
-
-makeoptions	TRAMPLOADADDR=0xffffffff85000000
-makeoptions	TRAMP_ARCH_FLAGS="-mabi=64 -march=mips64"