Created attachment 168861 [details] lspci -vvv -s 00_02.0 Screen LVDS1 turns black early at boot with kernel 3.14 The computer is a laptop and has been used with an external screen plugged (VGA) for several months. After unplugging the VGA from the laptop I was getting a black screen at boot. Grub2 screen is ok but in the very early stage at boot just after showing the first few kernel lines the built-in screen turns black. CTRL-ALT-F1 + CTRL-ALT--F7 does not help. Built-in screen stays black until a VGA is plugged. With the VGA plugged (even when it's power is off) the boot is normal with all the boot messages visible on the built-in screen. This behaviour is reproducible: VGA plugged: Screen is ok VGA unplugged: Screen tuns black at boot The problem seems to be fixed later in kernel v3.15
Created attachment 168871 [details] dmesg without VGA plugged
Created attachment 168881 [details] reverse git bisect I did a reverse git bisect leading to 484b41dd70a9fbea894632d8926bbb93f05021c7 $ git branch --contains 484b41dd70a9fbea894632d8926bbb93f05021c7 master $ git tag --contains 484b41dd70a9fbea894632d8926bbb93f05021c7 v3.15 v3.15-rc1 v3.15-rc2 v3.15-rc3 v3.15-rc4 ... until ... v3.19-rc6 v3.19-rc7 Checked out v.3.15 for testing and was ok.
Created attachment 168891 [details] Kernel configuration
Thanks for the reverse bisect, however the commit is too big to be backported to stable kernels. Please upgrade to v3.15 or later. Thanks for the report.