you can download rescatux via this site http://www.supergrubdisk.org/rescatux/
load a live mint disk. follow these instructions to reinstall grub https://community.linuxmint.com/tutorial/view/245
Then boot into mint. then go to /etc/grub.d/40_custom file. in there you will paste everything from the qubes /boot partition. from /boot/grub/grub2/grub.cfg file (or something like that) the whole section between where it says xen. then update grub and reboot and qubes and windows should be in the mint grub.
As I tried to point out, I have already tried all possible partitions for root=(hdx,y), including hd0,6 and none of them worked.
I'd prefer fixing it without a life distro by mounting the mint partition on qubes. Which files do I have to get and paste to the /boot partition? And how do I paste them there? Is the /boot partition the folder /boot in the dom0 filesystem?
If not i suggest u use rescatoox because its most simple way.
just saying what i find simpler, and how I do it myself.
And are the changes I made persistent if I update-grub? (I'm not planning to do that but if I do in a year or so I probably won't remember if it is not persistent)
what fixed it? What commands? Are you booting qubes from a mint grub? If you doint the /etc/grub.d/40_custom method. make sure to paste in ther eeverything in the qubes grub.cfg between where it starts ### BEGIN /etc/grub.d/20_linux_xen ###
Its persistent but when qubes upgrade a kernel or initrd or something you will want to repeat this step and do update-grub again.
This variables
recordfail
gfxmode
are not needed,coment it or delete.Then boot should be clean with no errors.
ok well then if he copied the menuentry or pasted from the mint boot partition's grub.cfg then its just opposite. might want to update it if mint updates its kernel.