r343567 aka PAE vs non-PAE merge breaks i386 freebsd

r343567 merges the PAE vs non-PAE pmap headers for i386
freebsd.  After bisection and dealing with the drm-legacy-kmod
fallout, I bisected /usr/src to r343567.  Building world and
a GENERIC kernel and the minimum set of ports to start Xorg
on my Dell Latitude D530 laptop, results in a black screen
of death and a locked up laptop (no keyboard, mouse, or video).

A comparison of /etc/log/Xorg.0.log for r343566 (Xorg loads
and functions) and r353467 (Xorg black screen of death) shows
that /boot/modules/i915kms.ko loads correctly as the log
files are identical.

Comparing dmesg for r343566 to r343567 shows the following
 
--- dmesg.343566	2019-02-20 08:13:07.727202000 -0800
+++ dmesg.343567	2019-02-21 19:02:24.469562000 -0800
_at__at_ -3,11 +3,11 _at__at_
 Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
 	The Regents of the University of California. All rights reserved.
 FreeBSD is a registered trademark of The FreeBSD Foundation.
-FreeBSD 13.0-CURRENT r343566 GENERIC i386
+FreeBSD 13.0-CURRENT r343567 GENERIC i386
 FreeBSD clang version 7.0.1 (tags/RELEASE_701/final 349250) (based on LLVM 7.0.1)
 WARNING: WITNESS option enabled, expect reduced performance.
 VT(vga): resolution 640x480
-CPU: Intel(R) Core(TM)2 Duo CPU     T7250  _at_ 2.00GHz (1995.05-MHz 686-class CPU)
+CPU: Intel(R) Core(TM)2 Duo CPU     T7250  _at_ 2.00GHz (1995.04-MHz 686-class CPU)
   Origin="GenuineIntel"  Id=0x6fd  Family=0x6  Model=0xf  Stepping=13
   Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
   Features2=0xe3bd<SSE3,DTES64,MON,DS_CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM>
_at__at_ -16,7 +16,7 _at__at_
   VT-x: (disabled in BIOS) HLT,PAUSE
   TSC: P-state invariant, performance statistics
 real memory  = 4294967296 (4096 MB)
-avail memory = 3639914496 (3471 MB)
+avail memory = 4154175488 (3961 MB)

Somehow the r343567 kernel found an addition 490 MB of memory,
which leads me to believe the after loading i915kms.ko there
is some serious memory stomping issues.

I willing to do whatever is necessary to fix this issue (shorter
of mailing the laptop to someone).  Is it possible to revert
r343567 and move forward? 

-- 
Steve