I get a segfault when running intel_backlight:

[1] 87789 segmentation fault  intel_backlight

pid 87789 (intel_backlight), uid 0: exited on signal 11


System Information and Backtrace:

Laptop: Acer Aspire 5332

FreeBSD shelly 11.0-RELEASE-p2 FreeBSD 11.0-RELEASE-p2 #0: Mon Oct 24 06:55:27 UTC 2016
root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  amd64

Integrated Graphics Chipset: Intel(R) GM45

vgapci0@pci0:0:2:0:     class=0x030000 card=0x02121025 chip=0x2a428086 rev=0x09 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = 'Mobile 4 Series Chipset Integrated Graphics Controller'
    class      = display
--
vgapci1@pci0:0:2:1:     class=0x038000 card=0x02121025 chip=0x2a438086 rev=0x09 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = 'Mobile 4 Series Chipset Integrated Graphics Controller'
    class      = display

Using i915kms kernel module:

Id Refs Address            Size     Name
 1   26 0xffffffff80200000 1fa7c38  kernel
 2    1 0xffffffff821a9000 100ae8   i915kms.ko
 3    2 0xffffffff822aa000 55b0     iicbb.ko
 4    5 0xffffffff822b0000 6ec0     iicbus.ko
 5    2 0xffffffff822b7000 4480     iic.ko
 6    2 0xffffffff822bc000 881c0    drm2.ko
 7    1 0xffffffff82421000 587b     fdescfs.ko
 8    1 0xffffffff82427000 3775     acpi_video.ko

xorg version: xorg-7.7_2

(gdb) bt full
#0  reg_read (reg=819796) at intel_backlight.c:40
No locals.
#1  0x0000000000401d4c in main (argc=1, argv=0x7fffffffebe8) at intel_backlight.c:77
        current = 65535
        max = 0
        min = 0
        result = 0