Arch Linux

Altripp

Member

Registered: 2018-06-09

Posts: 1

Grub installed on partition can't automatically find Linux (dual boot)

First off: I wanted to make Grub my primary bootloader, but grub-mkconfig and os-prober wouldn't for the life of me find my windows 8. Yes, I mounted the partition where windows is installed and it still didn't work. So I decided to load grub from window's bootloader instead, since I didn't want to trash my windows Installation.

My relevant partitions are:
/dev/sda5 - /boot
/dev/sda6 - [SWAP]
/dev/sda7 - /
/dev/sda8 - /home

/dev/sdb1 - Windows install

So, I installed grub on the /boot partition with:
grub-install --target=i386-pc --debug --force /dev/sda5

(Yes, I know that this isn't standard, or even advisable. But I couldn't find any better way.)

And downloaded EasyBCD for windows, and added a new entry to my boot menu (Type: Grub 2, Drive: "Partition 3", as my Windows would see it, but the size matches with /dev/sda5, the /boot partition, 200M). Now I can select that new entry in the windows boot menu and I'm greeted with grub, like so:

GRUB4DOS 0.4.5c 2014-01-17, Mem: 630K/511M/2802M, End: 356539
[ Minimal BASH-like line editing is supported. For the first word, TAB
  lists possible command completions. Anywhere else TAB lists the possible
  completions of a device/filename. ]
grub> _

After some reading online, it seems like the computer somehow found some kind of grub, but couldn't locate/read its configuration file. I can boot into Arch just fine if I type the following commands:

grub> root=(hd1,4)
Filesystem type is ext2fs, partition type 0x83
grub> kernel=/vmlinuz-linux root=/dev/sda7 ro
   [Linux-bzImage, setup=0x4200, size=0x4fb370]
grub> initrd=/initramfs-linux.img
   [Linux-initrd @ 0x1f88a000, 0x7654c8 bytes]
grub> boot

Once I do that Arch boots just as expected, and everything works fine. I can 'less /boot/grub/grub.cfg' and it looks healthy, with a few menu entries for Arch. I already tried 'grub-mkconfig -o /boot/grub/grub.cfg' and it made no difference. Anyone has any idea what my issue is, or how to fix it?

Thanks in advance

bashM0nk3y

Member

From: the big she-bang

Registered: 2018-05-26

Posts: 49

Re: Grub installed on partition can't automatically find Linux (dual boot)

Why couldn't you just mount /boot on /dev/sda5 and issue the regular grub-install command?

Doesn't the grub UEFI install script ignore device paths?

Last edited by bashM0nk3y (2018-06-09 07:02:42)