root@somebox:~ # cat /var/crash/info.last
Dump header from device: /dev/ada0p4
  Architecture: amd64
  Architecture Version: 2
  Dump Length: 1617485824
  Blocksize: 512
  Compression: none
  Dumptime: Mon Sep 10 04:39:08 2018
  Hostname: somebox
  Magic: FreeBSD Kernel Dump
  Version String: FreeBSD 12.0-ALPHA3 #0 r338359: Wed Aug 29 21:49:53 EDT 2018
    bob@somebox:/usr/obj/usr/src/amd64.amd64/sys/GENERIC
  Panic String: kdb_switch: did not reenter debugger
  Dump Parity: 3296449130
  Bounds: 5
  Dump Status: good
root@somebox:~ # kgdb -n 5
GNU gdb 6.1.1 [FreeBSD]
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "amd64-marcel-freebsd"...

Unread portion of the kernel message buffer:


Fatal trap 12: page fault while in kernel mode
cpuid = 3; apic id = 03
fault virtual address   = 0x30
fault code      = supervisor read data, page not present
instruction pointer = 0x20:0xffffffff80b55fa4
stack pointer           = 0x28:0xfffffe008b74f190
frame pointer           = 0x28:0xfffffe008b74f190
code segment        = base 0x0, limit 0xfffff, type 0x1b
            = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags    = interrupt enabled, resume, IOPL = 0
current process     = 52726 (find)
Uptime: 1h25m1s
(ada0:ahcich2:0:0:0): spin-down
Dumping 1542 out of 16221 MB:..2%..11%..21%..31%..41%..51%..61%..71%..81%..91%

Reading symbols from /boot/kernel/i915kms.ko...Reading symbols from /usr/lib/debug//boot/kernel/i915kms.ko.debug...done.
done.
Loaded symbols for /boot/kernel/i915kms.ko
Reading symbols from /boot/kernel/drm.ko...Reading symbols from /usr/lib/debug//boot/kernel/drm.ko.debug...done.
done.
Loaded symbols for /boot/kernel/drm.ko
Reading symbols from /boot/kernel/linuxkpi.ko...Reading symbols from /usr/lib/debug//boot/kernel/linuxkpi.ko.debug...done.
done.
Loaded symbols for /boot/kernel/linuxkpi.ko
Reading symbols from /boot/modules/linuxkpi_gplv2.ko...done.
Loaded symbols for /boot/modules/linuxkpi_gplv2.ko
Reading symbols from /boot/modules/debugfs.ko...done.
Loaded symbols for /boot/modules/debugfs.ko
Reading symbols from /boot/modules/i915_kbl_huc_ver02_00_bin.ko...done.
Loaded symbols for /boot/modules/i915_kbl_huc_ver02_00_bin.ko
Reading symbols from /boot/modules/i915_kbl_dmc_ver1_01_bin.ko...done.
Loaded symbols for /boot/modules/i915_kbl_dmc_ver1_01_bin.ko
Reading symbols from /boot/kernel/if_iwm.ko...Reading symbols from /usr/lib/debug//boot/kernel/if_iwm.ko.debug...done.
done.
Loaded symbols for /boot/kernel/if_iwm.ko
Reading symbols from /boot/kernel/iwm8265fw.ko...Reading symbols from /usr/lib/debug//boot/kernel/iwm8265fw.ko.debug...done.
done.
Loaded symbols for /boot/kernel/iwm8265fw.ko
Reading symbols from /boot/kernel/uhid.ko...Reading symbols from /usr/lib/debug//boot/kernel/uhid.ko.debug...done.
done.
Loaded symbols for /boot/kernel/uhid.ko
Reading symbols from /boot/kernel/ums.ko...Reading symbols from /usr/lib/debug//boot/kernel/ums.ko.debug...done.
done.
Loaded symbols for /boot/kernel/ums.ko
Reading symbols from /boot/kernel/ng_ubt.ko...Reading symbols from /usr/lib/debug//boot/kernel/ng_ubt.ko.debug...done.
done.
Loaded symbols for /boot/kernel/ng_ubt.ko
Reading symbols from /boot/kernel/netgraph.ko...Reading symbols from /usr/lib/debug//boot/kernel/netgraph.ko.debug...done.
done.
Loaded symbols for /boot/kernel/netgraph.ko
Reading symbols from /boot/kernel/ng_hci.ko...Reading symbols from /usr/lib/debug//boot/kernel/ng_hci.ko.debug...done.
done.
Loaded symbols for /boot/kernel/ng_hci.ko
Reading symbols from /boot/kernel/ng_bluetooth.ko...Reading symbols from /usr/lib/debug//boot/kernel/ng_bluetooth.ko.debug...done.
done.
Loaded symbols for /boot/kernel/ng_bluetooth.ko
Reading symbols from /boot/kernel/ng_l2cap.ko...Reading symbols from /usr/lib/debug//boot/kernel/ng_l2cap.ko.debug...done.
done.
Loaded symbols for /boot/kernel/ng_l2cap.ko
Reading symbols from /boot/kernel/ng_btsocket.ko...Reading symbols from /usr/lib/debug//boot/kernel/ng_btsocket.ko.debug...done.
done.
Loaded symbols for /boot/kernel/ng_btsocket.ko
Reading symbols from /boot/kernel/ng_socket.ko...Reading symbols from /usr/lib/debug//boot/kernel/ng_socket.ko.debug...done.
done.
Loaded symbols for /boot/kernel/ng_socket.ko
Reading symbols from /boot/kernel/mac_ntpd.ko...Reading symbols from /usr/lib/debug//boot/kernel/mac_ntpd.ko.debug...done.
done.
Loaded symbols for /boot/kernel/mac_ntpd.ko
#0  cpustop_handler () at /usr/src/sys/x86/x86/mp_x86.c:1383
1383        CPU_SET_ATOMIC(cpu, &stopped_cpus);


(kgdb) list *0xffffffff80b55fa4
0xffffffff80b55fa4 is in prison_priv_check (/usr/src/sys/kern/kern_jail.c:2847).
2842     */
2843    int
2844    jailed(struct ucred *cred)
2845    {
2846
2847        return (cred->cr_prison != &prison0);
2848    }
2849
2850    /*
2851     * Return 1 if the passed credential is in a jail and that jail does not
(kgdb)