[SOLVED] Moving a Kernel Option into Grub?

jakfish · 08-04-2021, 02:18 PM

With these instructions here:

https://handheld.computer/?page_id=1131#kernel

I was able to compile a 8.7mb monolith kernel for my One-Netbook A1. The rub is, this is a gentoo-based kernel running on my Linux Mint 19.3 xfce. "Make install" created a kernel panic, so I used installed this way:

Code:

mount /dev/nvme0n1p1 /mnt/boot
cp arch/x86_64/boot/bzImage /mnt/boot/EFI/Boot/bootx64.efi
umount /mnt/boot
efibootmgr -c -d /dev/nvme0n1 -p1 -L 'Gentoo' -l '\EFI\Boot\bootx64.efi'

Now I boot directly into the gentoo kernel, but is it possible to put this kernel option into grub so I can choose easily b/w gentoo and the generic ubuntu kernel?

Thanks for any advice,
Jake

colorpurple21859 · 08-04-2021, 03:23 PM

at the grub menu when you first boot press c for grub> prompt,

Code:

grub> chainloader (hd0,1)/EFI/Boot/bootx64.efi

is able to boot gentoo,

add an menuentry similar to this in /etc/grub.d/40_custom

Code:

menuentry 'Gentoo' {
set root=(hd0,1)
chainloader=/EFI/Boot/bootx64.efi
}

then rerun update-grub

jakfish · 08-04-2021, 03:52 PM

Many thanks for your quick reply. With "(hd0,1)", bootx64.efi is not found.

ls produces, in this order: (proc) (hd0) (hd0,msdos) (hd1) (hd1, gpt7) (hd1, gpt6) (hd1, gpt5) (hd1, gpt4) (hd1, gpt3) (hd1, gpt2) (hd1, gpt1)

Chainloading gpt1 or gpt6 appears to find the file, but gentoo doesn't load, things errorlessly return to grub prompt.

Thanks again for weighing in,
Jake

I don't know if this helps, but this is where I find the *.efi: /boot/efi/EFI/Boot/bootx64.efi

colorpurple21859 · 08-04-2021, 08:23 PM

based on

Quote:

mount /dev/nvme0n1p1 /mnt/boot

add this to the mix at the grub prompt

Code:

grub> chainloader (hd1,gpt1)/EFI/Boot/bootx64.efi
grub> boot

another menuentry in /etc/grub.d/40_custom that may work is

Code:

menuentry 'Gentoo' {
set root=(hd1,gpt1)
linux /EFI/Boot/bootx64.efi
}

jakfish · 08-04-2021, 09:09 PM

That did it. Thanks once more for figuring this out.

One thing--could you tell me why

Code:

grub> boot

was necessary in this case? I'm still working through the mechanics of chainloading.

Jake

colorpurple21859 · 08-04-2021, 09:19 PM

I had forgot to add boot in my original post. boot is needed when booting from the grub prompt to tell grub to boot the system.

jakfish · 08-05-2021, 08:15 AM

Got it. Thanks for the explanation.

Jake

jakfish · 08-05-2021, 08:29 AM

An interesting quirk--booting into Win10 from grub works, but upon reboot, the Gentoo option disappears from grub. I have to boot into Linux Mint via ubuntu generic kernel, and re-reun update-grub to get Gentoo option back.

Any idea why?

Jake

colorpurple21859 · 08-05-2021, 09:17 AM

Quote:

Chainloading gpt1 or gpt6 appears to find the file

Do you have two efi partitions? There may be another grub.cfg located somewhere else that is loaded instead of the one with the gentoo menu entry, possibly located on the efi partition somewhere.

jakfish · 08-05-2021, 10:32 AM

There's only one efi partition and only one grub.cfg, found in /boot/grub.

Perhaps Win10's boot is scrambling things as linux-to-linux reboots are fine, grub-wise.

For me, Win10 is basically a 25gb Netflix viewer, so I don't often boot there.

Jake