Grub does not detect-see second kernel

Good evening ,
I installed the default lts kernel, but it warms up a lot, so I added another non-lts kernel, and I gave:
mkinitcpio -p linux
but grub does not detect it, there is someone who can tell me the command to show grub, the second kernel, I searched the web, but I can not find anything.
Thank for help

That mkinitcpio command will just regenrate the initramfs for the stock Arch kernel:

To update GRUB’s configuration use grub-mkconfig -o /boot/grub/grub.cfg (as root).

EDIT: that’s in the ArchWiki as well:

i tremove grub and install bootctl.
Thank to all

^That’s not a solution, it’s a workaround.

Does grub-mkconfig work?

No, it does not work.
So, let me explain, better:
I installed the old and new version on a usb thoshiba-ext, in gpt-efi, (/ boot).
every distro with his fat, since I installed the second distro always archlabs, the first distro no longer started, nor from chroot giving the command to generate grub, as you said.
Same thing removing grub from the second distro (the last installed) and then giving back your command from the first distro, it always gave me kernel panic.

So you mounted /boot in both ArchLabs systems to the EFI system partition?

There is no “old” or “new” version of ArchLabs, it is a rolling-release distribution so there is only ever one version available and that is the very latest version.

If you keep both systems up to date and synchronised then they should be able to share a single kernel version, I suspect your problem was due to a mismatched kernel version between the two systems.

Not, every distro had its fat / boot, so I do not understand why, once the last relase was installed, it did not leave me anymore, the first distro.
Even by redoing the chroot with grub, I was not able to restart it.
That’s why, I moved on bootctl