Panic when starting X with Intel KMS

[Michael Butler]

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I wrote:

> Post SVN r252653, I have experienced a similar problem but I'm not sure
> it's related ..

This is related to SVN r252653 - reverting it solves the instances of
the panic detailed below.

The recent modification to amd64 addresses the issue but does nothing to
help this CPU ..

CPU: Genuine Intel(R) CPU           T2300  @ 1.66GHz (1662.53-MHz
686-class CPU)
  Origin = "GenuineIntel"  Id = 0x6e8  Family = 0x6  Model = 0xe
Stepping = 8

Features=0xbfe9fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0xc1a9<SSE3,MON,VMX,EST,TM2,xTPR,PDCM>
  TSC: P-state invariant, performance statistics

 .. which claims to have ..

imb at toshi:/home/imb> sysctl vm.pmap
vm.pmap.pv_entry_count: 627756
vm.pmap.pde.promotions: 20165
vm.pmap.pde.p_failures: 44416
vm.pmap.pde.mappings: 0
vm.pmap.pde.demotions: 19659
vm.pmap.shpgperproc: 200
vm.pmap.pv_entry_max: 2000208
vm.pmap.pg_ps_enabled: 1
vm.pmap.pat_works: 1

Perhaps an equivalent patch to i386/pmap.c is appropriate here?

> root at toshi:/var/crash # less info.1
> Dump header from device /dev/ada0s3b
>   Architecture: i386
>   Architecture Version: 2
>   Dump Length: 205541376B (196 MB)
>   Blocksize: 512
>   Dumptime: Sat Jul 20 15:21:39 2013
>   Hostname: toshi.auburn.protected-networks.net
>   Magic: FreeBSD Kernel Dump
>   Version String: FreeBSD 10.0-CURRENT #5 r253505M: Sat Jul 20 14:48:32
> EDT 2013
>     imb at toshi.auburn.protected-networks.net:/usr/obj/usr/src/sys/TOSHI
>   Panic String: bad pte
>   Dump Parity: 854235148
>   Bounds: 1
>   Dump Status: good
> 
> root at toshi:/var/crash # kgdb /boot/kernel.old/kernel vmcore.1
> 
>  [ snip ]
> 
> #0  0xc07b814c in doadump ()
> (kgdb) bt
> #0  0xc07b814c in doadump ()
> #1  0xc07b86ec in kern_reboot ()
> #2  0xc07b8b68 in panic ()
> #3  0xc0b20b1d in pmap_remove_pages ()
> #4  0xc0aa43dd in vmspace_exit ()
> #5  0xc07814bf in exit1 ()
> #6  0xc07ba5d5 in sigexit ()
> #7  0xc07bd35f in postsig ()
> #8  0xc0804e1b in ast ()
> #9  0xc0b132b7 in doreti_ast ()
> #10 0xf1633d08 in ?? ()
> #11 0x2c00003b in ?? ()
> #
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