Baytrail (server) machines can't be booted up without a monitor connected, because hotplug doesn't work without X. This has been fixed upstream in v4.8-rc1, four commits need to be backported:
4570d833390b100 drm/i915/vlv: Make intel_crt_reset() per-encoder
4c732e6ee9e7190 drm/i915/vlv: Reset the ADPA in vlv_display_power_well_init()
21842ea84f161ae drm/i915/vlv: Disable HPD in valleyview_crt_detect_hotplug()
84c8e0963da434d drm/i915: Enable polling when we don't have hpd
Baytrail (server) machines can't be booted up without a monitor connected, because hotplug doesn't work without X. This has been fixed upstream in v4.8-rc1, four commits need to be backported:
4570d833390b100 drm/i915/vlv: Make intel_crt_reset() per-encoder power_well_ init() crt_detect_ hotplug( )
4c732e6ee9e7190 drm/i915/vlv: Reset the ADPA in vlv_display_
21842ea84f161ae drm/i915/vlv: Disable HPD in valleyview_
84c8e0963da434d drm/i915: Enable polling when we don't have hpd