#788845 grub: grub fails to boot when no monitor is connected

Package:
grub-common
Source:
grub2
Description:
GRand Unified Bootloader (common files)
Submitter:
"Roger Pueyo Centelles | Guifi.net"
Date:
2015-06-15 14:21:05 UTC
Severity:
important
#788845#5
Date:
2015-06-15 14:12:17 UTC
From:
To:
Dear Maintainer,

I have installed Debian Jessie 8.1 on several Minix Z64-A, a mini-PC based on an Intel Atom Z3735F CPU with a 64 bits EFI BIOS. After rebooting several times, I've noticed that the system does not boot if no monitor is connected to the HDMI port. The system goes past the BIOS (during this time, the NumLock keyboard LED responds to the key presses) but then freezes and does not do anything else (keyboard does not respond and connecting the monitor back does not show anything). Only  powercycling the device with the monitor plugged makes it boot normally. Identical behaviour has been identified with grub packages 2.02~beta2.-22 (Jessie), 2.02~beta2.23 (Stretch) and 2.02~beta2.26 (Sid), after upgrading, reinstalling grub2 to the device and updating the configuration (grub-install /dev/mmcblk0, update-grub).

Interestingly, installing Ubuntu Wily's grub packages 2.02~beta-23ubuntu1 allows booting without a monitor connected, but grub menu is not displayed at all after the BIOS and before booting the kernel.