Re: [gentoo-user] Re: OFF TOPIC Need Ubuntu network help: boot loader info

[Michael <confabulate@kintzios.com>]

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On Thursday, 19 October 2023 05:49:25 BST Dale wrote:
> Neil Bothwick wrote:
> > On Wed, 18 Oct 2023 17:27:28 -0500, Dale wrote:
> >> I used cgdisk and GPT for my disk even tho it is small, only 300GBs or
> >> so, mostly out of habit.  The grub install failed and I did a search.  I
> >> found this and it worked. 
> >> 
> >> 
> >> 
> >> grub-install fails with "grub-install: warning: this GPT partition label
> >> contains no BIOS Boot Partition; embedding won't be possible." 

If you are booting a BIOS MoBo, or an EFI MoBo in 'BIOS Legacy' mode, from a 
disk which contains a GPT partitioning scheme, then you will need a separate  
partition created as type 'BIOS Boot Partition' for GRUB to install its 
core.img:

GRUB's Stage 1 boot.img is still installed in sector 0 on a GPT disk, same as 
on a disk with an MBR partition table.  However, on a GPT disk GRUB's Stage 
1.5 core.img with all its filesystem drivers has to be installed in a 
partition of its own, because unlike an MBR disk sectors 1 to 62 are not empty 
but contain the GPT header and the GPT partition list.  Without its filesystem 
drivers GRUB won't be able to access its modules in its Stage 2 filesystem, 
which is stored in the OS /boot/ partition, or its grubx64.efi UEFI 
executable.

It helps to get straight before you start an installation what combo of MoBo 
and type of disk partition tables you intend to use:

BIOS Vs EFI
MBR Vs GPT


> > Simple answer, don't use GRUB :-)
> > 
> > Seriously, GRUB is a bootloader, EFI is a bootloader. You are using one
> > bootloader to load another bootloader before booting the system.
> > 
> > rEFIind and systemd-boot are both boot managers, they work with the EFI
> > bootloader - or you can boot a kernel directly without a boot manager,
> > but I prefer not to do that as it gives no opportunity to edit options
> > when booting.

I like rEFIind, but I recall it needs/needed a separate /boot partition if you 
are running LVM/RAID.


> > If you like simple, here is a config file I use with systemd-boot
> > 
> > version 6.1.57-gentoo
> > linux   /vmlinuz-6.1.57-gentoo
> > options root=/dev/sda3 panic=10 net.ifnames=0 i915.enable_ips=0
> > 
> > That's it! There is a separate file for each menu entry, but they are
> > this simple. There's also a global loader.conf, that runs to a massive 2
> > lines here!
> 
> Right now, I'm still using BIOS type boot.  I've read where you and a
> couple others use something else and they do sound good but I just
> haven't got the nerve up to switch.  When I build a new rig, I'll likely
> get into some other boot manager.  In a way I kinda dread it but on the
> other hand, I just might like it.  You and several others make the other
> options sound really good. 
> 
> That config kinda reminds me of the old grub.  A title line, location of
> kernel and then options.  Sounds easy enough.  The new grub config is
> almost impossible to config by hand.  They had to make a tool to do it. 
> That says a lot there.  ;-) 

Not really, the GRUB developers were trying to make maintaining a boot manager 
simpler by scripting the process and offering to hook it up from binary 
distros' kernel install scripts.  Anyway, you can still write the 
configuration by hand if you follow the GRUB2 syntax.  You do not need to run 
GRUB's grub-mkconfig script to automatically update the grub.cfg file if you 
prefer to do it manually, but it is certainly simpler to use it since it is 
already there for you.


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