On 10/18/19 10:40 PM, akpm@linux-foundation.org wrote:
> The mm-of-the-moment snapshot 2019-10-18-22-40 has been uploaded to
> 
>    http://www.ozlabs.org/~akpm/mmotm/
> 
> mmotm-readme.txt says
> 
> README for mm-of-the-moment:
> 
> http://www.ozlabs.org/~akpm/mmotm/
> 
> This is a snapshot of my -mm patch queue.  Uploaded at random hopefully
> more than once a week.

Reported-by: Randy Dunlap <rdunlap@infradead.org>

on x86_64:

# CONFIG_ACPI is not set
CONFIG_BACKLIGHT_CLASS_DEVICE=m
CONFIG_BACKLIGHT_GENERIC=m
CONFIG_DRM_I915=y

ld: drivers/gpu/drm/i915/display/intel_panel.o: in function `intel_backlight_device_register':
intel_panel.c:(.text+0x39b3): undefined reference to `backlight_device_register'
ld: drivers/gpu/drm/i915/display/intel_panel.o: in function `intel_backlight_device_unregister':
intel_panel.c:(.text+0x3a64): undefined reference to `backlight_device_unregister'


Full randconfig file is attached.

-- 
~Randy