Setting GRUB 2 default menu entry

[Francesco Turco]

Hello.

I'm running GRUB 2.00 on a Gentoo Linux system.

I compile my own kernels manually, and then I install them in /boot with
make install. I have the following kernels in /boot at the moment:

# ls -1 /boot/vmlinuz*
/boot/vmlinuz-3.7.4-gentoo-5
/boot/vmlinuz-3.7.4-gentoo-first
/boot/vmlinuz-3.7.4-gentoo-fourth
/boot/vmlinuz-3.7.4-gentoo-third

Running grub2-mkconfig results in the following output:

# grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-3.7.4-gentoo-third
Found linux image: /boot/vmlinuz-3.7.4-gentoo-fourth
Found linux image: /boot/vmlinuz-3.7.4-gentoo-first
Found linux image: /boot/vmlinuz-3.7.4-gentoo-5
done

If I now read the resulting /boot/grub2/grub.cfg file, I notice that the
following entries have been created:

- A main default entry which starts vmlinuz-3.7.4-gentoo-third
- A submenu with the all the other entries (including recovery ones), in
the same order as the grub2-mkconfig command

The problem is that at boot time I'd like to load by default the fifth
revision of my kernel (vmlinuz-3.7.4-gentoo-5), not the third one
(vmlinuz-3.7.4-gentoo-third). I also prefer not to access the submenu
for choosing the right kernel to load.

How can I change this behaviour? How can I tell GRUB that I want to run
the fifth revision of my kernel by default and not the older third
revision? In general, how can I change the default entry line to match
the kernel I want and not a seemingly random one picked by GRUB?

I also tried with setting GRUB_DEFAULT=3 in /etc/default/grub and
re-running grub2-mkconfig. But at boot time the default entry is still
vmlinuz-3.7.4-gentoo-third.

Another problem I noticed with the GRUB_DEFAULT approach is that it
seems that you first have to run grub2-mkconfig for having the orderded
list of kernels, then you set that variable with the number of kernel
you want to load by default, but at last you have to re-run
grub2-mkconfig in order for the variable to take effect.

Thank you.