Your system is a mess tbh, you have EFI System partition with qubes xen/initamfs files but without grub files.
So I can only guess that you’re booting Qubes OS in Legacy mode?
And it seems that you’ve installed Kali in Legacy mode as well.
I don’t know how to configure multibooting properly for Legacy mode so I can’t help here.
Maybe someone else that use multibooting in Legacy boot mode can help out.
It was hard for me and it took me a long time to install and make Qubes work on my notebook, as you can see in this post, (one of the reasons being my hardware is old):
and the conversation continued with many more questions from me here:
I don’t really remember why I installed it in legacy mode, as you have more knowledge than me about Qubes, maybe you can deduct it from those messages?. Do you think it may also work in UEFI mode for my hardware? Do I need to reinstall both operative systems for that?
I remember I had a smaller SSD and then I upgraded to a bigger one, so I am not 100% sure if all that long process was done with the actual SSD as well. I don’t remember using any disk’s cloning software so I probably installed Qubes again in the new SSD.
It’s not guaranteed that UEFI will work right away, maybe you’ll need to use some custom options to make it work.
As I understand it, this part of guide:
Multibooting Qubes
Would be appropriate for your case if you’ve installed the Kali Linux on separate disk with its own GRUB installed.
But since you’ve installed the Kali on the same disk you should’ve followed this part of the guide:
Multibooting Qubes
I solved it this way:
On dom0, thunar, I’ve looked for the absolute (complete) route for the Kali’s partition and copied it into the clipboard.
On dom0, terminal I run: sudo nano [that-location]/boot/grub/grub.cfg
and copied to the clipboard the menuentry Kali GNU/Linux (at ### BEGIN /etc/grub.d/10_linux ###). Those were 17 lines including the } on the last line. Then I run:
sudo nano /boot/grub2/grub.cfg and pasted it after the end of the menuentry 'Qubes, with Xen hypervisor' (marked with a })
However I think this is not the best way to do it as that file warns DO NOT EDIT THIS FILE. I will probably try later to edit /etc/grub.d/40_custom and then run sudo upgrade-grub.
This was thanks to user @alzer89 who answered my pm with instructions and @apparatus who also spent time on my problem. (ChatGPT was useless in this case). Now I need to make it survive updates, maybe I can make an script that inserts the code into the grub file and execute that script inside /etc/apt/apt.conf.d/99post-update ? Maybe there is a simpler way?
Placing the Kali grub menu entry in /etc/grub.d/40_custom should work.
But you may need to manually update this entry after Kali kernel update.