Re: r343567 aka PAE vs non-PAE merge breaks i386 freebsd

On Thu, Feb 21, 2019 at 07:39:25PM -0800, Steve Kargl wrote:
> 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? 
> 

More info from sysctl.  With the "good" r343566, I see

vm.kmem_map_free: 1187033088
vm.kmem_map_size: 27234304
vm.kmem_size_scale: 3
vm.kmem_size_max: 1715470336
vm.kmem_size_min: 12582912
vm.kmem_zmax: 65536
vm.kmem_size: 1214267392
hw.physmem: 3714269184
hw.usermem: 3650867200
hw.realmem: 4294963200

With the problematic r343567, I see

vm.kmem_map_free: 1683152896
vm.kmem_map_size: 28123136
vm.kmem_size_scale: 1
vm.kmem_size_max: 1711276032
vm.kmem_size_min: 12582912
vm.kmem_zmax: 65536
vm.kmem_size: 1711276032
hw.physmem: 4252360704
hw.usermem: 4146999296
hw.realmem: 4294963200

Ideas?

-- 
Steve