Current partition is primary Arch and have another OS partition on mounted dir. named /mnt/OSraw/
So just try to go on updating it by the current updated primary OS partition by:
$ sudo pacman --sysroot /mnt/OSraw/ -S linux linux-firmware base
but then got:
error: could not open file: /etc/mtab: No such file or directory
error: could not determine filesystem mount points
error: failed to commit transaction (unexpected error)
Errors occurred, no packages were upgraded.
How to do the correct way ?
If possible use "chroot" to enter to the second OS environment. then use normal "pacman" command to update.
but if you still insist on using "--sysroot" flag, just follow arch wiki (https://wiki.archlinux.org/title/Pacman#Pacman_crashes_during_an_upgrade)