Installed Fedora 38 (sway) / grub2 on a new HD - boots OK but does not have a menuentry item in grub.cfg ?

[Philip Rhoades]

People,

My Fedora WS has 4 drive bays and I access old boot and other HDs in 
bays 2-4.  I just did a clean install of Fedora Sway to /dev/sda - 
everything is fine and the system boots OK but I am confused:

- cat /etc/os-release

NAME="Fedora Linux"
VERSION="38 (Sway)"
.
PRETTY_NAME="Fedora Linux 38 (Sway)"
ANSI_COLOR="0;38;2;60;110;180"
.
VARIANT="Sway"
VARIANT_ID=sway

- The install picked up old Fedora boot setups which show up in 
/boot/grub2/grub.conf like this:

menuentry 'Fedora Linux 37 (KDE Plasma) (on /dev/sde3)' --class 
gnu-linux --class gnu --class os $menuentry_id_option 
'osprober-gnulinux-/boot/vmlinuz-6.0.7-301.fc37.x86_64--f6f43412-e6ed-4dff-808b-fe013691c3b6' 
{

- but why is there is not a line like this in /boot/grub2/grub.conf for 
Fedora 38 Sway?

I can see that the appropriate other Sway files are in the /boot tree so 
I am guessing that grub2 somehow knows the proper, default boot image - 
even though the default does not have a menuentry in grub.cfg?

A pointer to a link for info would be great . .

Thanks!

Phil.

Hi.

On Sat, 22 Apr 2023 16:37:53 +1000 Philip Rhoades via users wrote:
> but why is there is not a line like this in /boot/grub2/grub.conf for
>
> Fedora 38 Sway?
> I can see that the appropriate other Sway files are in the /boot tree so 
> I am guessing that grub2 somehow knows the proper, default boot image - 
> even though the default does not have a menuentry in grub.cfg?

I bet it's related to BootLoaderSpec. If you look at the

### BEGIN /etc/grub.d/10_linux ###

section of grub.cfg you will see:

# The blscfg command parses the BootLoaderSpec files stored in
  # /boot/loader/entries and populates the boot menu. Please refer to the Boot
  # Loader Specification documentation for the files format:
  # https://systemd.io/BOOT_LOADER_SPECIFICATION/.

[Philip Rhoades]

Francis,

On 2023-04-22 17:18, [e-mail] wrote:
> Hi.
>
> On Sat, 22 Apr 2023 16:37:53 +1000 Philip Rhoades via users wrote:
> > but why is there is not a line like this in /boot/grub2/grub.conf
> >
> > for
> > Fedora 38 Sway?
> > I can see that the appropriate other Sway files are in the /boot tree 
> > so
> > I am guessing that grub2 somehow knows the proper, default boot image
> >
> > even though the default does not have a menuentry in grub.cfg?
>
> I bet it's related to BootLoaderSpec. If you look at the
>
> ### BEGIN /etc/grub.d/10_linux ###
>
> section of grub.cfg you will see:
>
> # The blscfg command parses the BootLoaderSpec files stored in
>   # /boot/loader/entries and populates the boot menu. Please refer to 
> the Boot
>   # Loader Specification documentation for the files format:
>   # https://systemd.io/BOOT_LOADER_SPECIFICATION/.

Ah - that sounds promising! - I will have a look at that - I would like 
a better understanding of how grub2 operates before I start messing 
around with adding entries to grub.cfg manually . .

Thanks!

Phil.