gentoo boot media won't boot - blank screen [SOLVED]

mark_lagace · Last edited by mark_lagace on Sat Jun 22, 2019 2:10 am; edited 1 time in total

I'm trying to run Gentoo on a Gigabye Brix GB-BLCE-4105 ultra compact PC, but can't get it to boot. I have tried with an existing SSD that has a functional Gentoo install from another system, and with the minimal install CD downloaded from the web. I tried both with it burned onto a DVD and on a USB drive. In all cases, the UEFI detects the media and identifies it as bootable, but when I select it to boot I get a blank screen (sometimes with what looks like an underscore cursor in the upper left corner of the screen) and nothing happens.

What I have tried:
Secure boot on and off in the bios.
(There's no legacy bios on this system so it's UEFI or nothing...)
Booting from an Ubuntu 18.04 live USB (which works), chrooting into my Gentoo disk, and reinstalling grub. Everything appears to work (no errors, grub-mkconfig finds the right kernel etc.)
Trying boot-repair from the Ubuntu live install - doesn't seem to work properly as I'm fairly certain it's looking for a Ubuntu installation.
Copying the grubx64.efi file into the EFI/boot directory and renaming it bootx64.efi

I honestly don't know where to go from here. I've got no error messages to work with to help narrow down the problem. The system simply doesn't boot. An old systemrescuecd also wouldn't boot, but the newer one (6.02) which I believe is based on Arch does. At this point, I'm just looking for suggestions on how to track down the problem - searching for blank screen, or grub won't boot etc. in Google has so far pulled up nothing useful.

389292 · Guru Joined: 26 Mar 2019 Posts: 504

What you change when you use Ubuntu image? Do you use the same flash drive? How do you flash it? Do you use the same USB port at all attempts? Do you always use secure boot off + uefi boot entry?

mark_lagace · Posted: Thu Jun 20, 2019 8:54 pm Post subject:

I've used a different usb key, but the same port and bios settings. The Gentoo minimal install usb does boot on my other computer so I am confident that the usb key is fine.

EDIT: Just to completely eliminate a bad USB key from the picture, I overwrote the Ubuntu USB key with the gentoo install. I tried both minimal install and the live DVD and neither will boot. As before, the system sees them as bootable, but I get a blank screen and nothing happens when I select it as my boot device. Re-flashing the USB with Ubuntu 18.04.2 and it boots fine.

mark_lagace · Posted: Sat Jun 22, 2019 2:16 am Post subject:

For posterity - I've managed to solve my booting issue. When I copied the grubx64.efi file from the ubuntu boot media to my EFI partition, I was able to get to a grub shell and then manually boot my kernel that way, which led me to believe the issue was with either grub or it's config files. I tried adjusting the settings (particularly around the GFX MODE and other similar settings) but could not get it to boot. However, clearing all of the grub configuration files from /etc/grub.d and /etc/default/grub and emerging and installing the latest ~amd64 grub (2.04...) worked.