I have 2 disks:
1-st disk contains base operating system (/dev/sda with many partitions and OSes)
2-nd disc should be setup (/dev/sdb1=/boot,/dev/sdb2=/)
I have grub2 package installed in the base operating system. I want to create grub.config file for the operating systems on the second disk (without installing grub2 package in chroot on second disk, because this disk is for different architecture. I just want to regenerate config)
if I use
mkdir -p /mnt/gentoo mount /dev/sdb2 /mnt/gentoo mount /dev/sdb1 /mnt/gentoo/boot grub-mkconfig -o /mnt/gentoo/boot/grub/grub.cfg
then there is no way to specify /dev/sdb as a base disk for enumerating installed OSes for grub-mkconfig
If disk /dev/sda contains N partitions, then grub-mkconfig creates ~ N * number_of_kernels menu entries. But I want make it creating entries for partitions of disk /dev/sdb (which have one partition /dev/sdb2 with one installed OS).
I also tried grub-customizer utility, because it have disk selection in parameters dialog. But looks like grub-customizer uses all utilities and files which are relative to the choosen disk, and I don't have grub2 on /dev/sdb installed (see note above about different architecture)
Someone told me that it is possible to do this by temporary correcting fstab of base system, but I doubt this will help.
So, how to generate grub.conf for different disk? (without writing it by hands with texteditor)
UPD: feature request - https://savannah.gnu.org/bugs/index.php?44129