I'm using a MacBook Pro (Mid-2012 model; MacBookPro9,2), dual-booting OS X Yosemite with Ubuntu 15.04, and I'm having an issue with the keyboard backlight brightness.
Apparently this issue has been around for a long time, especially on Macs, with display brightness too, not just the keyboard backlight, but the reason was altogether different. This seems to have been resolved in 15.04 with systemd now setting the brightness for display and keyboard backlight, with one caveat -- it won't set either to zero.
This is fine, even desired, for the display -- if I set the display to zero brightness and reboot, it's then set to 1/15 on boot. However, if I set the keyboard backlight to zero brightness, it's set to 255/255 (i.e. 100%) on reboot. Note that all this is completely fine for non-zero values; they're remembered and restored perfectly.
Also, even though the values aren't "remembered" on reboot, systemd is still storing the correct value of
0 in the two files in
/var/lib/systemd/backlight/, which are
platform-applesmc.768:leds:smc::kbd_backlight for the display and keyboard backlight, respectively.
So is there any way to change this behaviour? If I set the keyboard backlight off and reboot, it should remain off after all, not blind me on reboot...