Re: [gentoo-user] Exact setting in grub to default to a kernel by name?

[Michael <confabulate@kintzios.com>]

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On Sunday, 13 June 2021 19:05:29 BST Neil Bothwick wrote:
> On Sun, 13 Jun 2021 09:33:57 -0400, Walter Dnes wrote:
> > On Sun, Jun 13, 2021 at 06:46:15AM +0200, Hund wrote
> > 
> > > >Let me rephrase the question more generally... given a
> > > >kernel "/boot/vmlinuz-fubar" how and where do I specify it by name as
> > > >the default boot kernel?
> > > 
> > > What about this?
> > > 
> > > https://www.stephenrlang.com/2017/06/setting-default-kernel-in-grub2/
> > > 
> >   Is /boot/grub/grub.cfg the file that actually controls bootup, and is
> > 
> > all 154 lines of verbosity really necessary?  For menu entries I see...
> 
> Not necessary, but does no harm either. The first 90% of the file is
> automated setup, which you can replace with hard coded entries or just
> leave it to its own devices. The only part you need to think about is the
> menuentry sections.
> 
> >   I'd be tempted to do a manual gub.cfg if I had documentation.
> 
> GRUB has extensive documentation. it's not the best written but every
> configuration option is described.
> 
> Isn't this a new laptop? If so, why torment yourself with GRUB when you
> have UEFI available to you? The only real justification for using GRUB in
> such a situation is that you are completely familiar with it and don't
> want to learn something else. But if you have to learn something, you may
> as well learn the 2/3 line configs of systemd-boot.
> 
> Note that systemd-boot doesn't require systemd, it's just the gummiboot
> boot manager that was merged into systemd taken out again. Or you could
> use rEFInd if you prefer a prettier boot menu.

I do like rEFInd, feels AppleMac-like.  :-)

However, I have abandoned all boot managers these days on UEFI MoBos and just 
use the native UEFI firmware to boot with.[1]  It's simpler, lighter and 
faster.  However, I don't boot into different OS/kernels unless I have to and 
when I do I have to use the UEFI menu GUI to switch OS/kernels, so this won't 
suit all use cases.

This approach requires to enable the 'EFI boot stub' option in the kernel, so 
that the UEFI firmware can recognise and load the kernel directly as an EFI 
executable.[2]  Then it is a matter of using the efibootmgr on the CLI to set 
up my boot menu labels and OS/kernel order.[3] 

[1] https://wiki.gentoo.org/wiki/Handbook:AMD64/Installation/
Bootloader#Alternative_2:_efibootmgr
[2] https://wiki.gentoo.org/wiki/EFI_Stub
[3] https://wiki.gentoo.org/wiki/Efibootmgr

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