How to flash image (.iso) to paritition
- Create partition
 
sudo fdisk /dev/sda
- Format partition
 
sudo mkfs.ext4 /dev/sda11
- Write image to partition
 
sudo dd bs=4M if=/home/stroky/Downloads/cachyos-desktop-linux-241110.iso of=/dev/sda11 status=progress oflag=sync
- Mount partition
 
sudo mount /dev/sda11 /mnt/cachyos
- Check for the grub.cfg in there
 
ls /mnt/cachyos/boot/grub/
- Add entry
 
sudoedit /etc/grub.d/40_custom
There are 3 main ways
- Direct provide path for grub.cfg:
 
menuentry 'CachyOS Install direct' {
    set root=(hd1,gpt11)
    configfile /boot/grub/grub.cfg
    # linux ($root)/arch/boot/x86_64/vmlinuz-linux-cachyos root=/dev/sda11 ro quiet splash 
    # initrd ($root)/arch/boot/x86_64/initramfs-linux-cachyos.img
}
- Boot through partition:
 
menuentry 'CachyOS Install dev11' {
    set root=(hd1,gpt11)
    linux ($root)/arch/boot/x86_64/vmlinuz-linux-cachyos root=/dev/sda11 ro quiet splash cow_spacesize=10G
    initrd ($root)/arch/boot/x86_64/initramfs-linux-cachyos.img
}
- Boot through iso:
 
menuentry 'CachyOS Install' {
    set isofile="/home/stroky/Downloads/cachyos-desktop-linux-241110.iso"
    loopback loop $isofile
    linux (loop)/arch/boot/x86_64/vmlinuz-linux-cachyos img_dev=/dev/sda8 img_loop=$isofile earlymodules=loop cow_spacesize=10G
    initrd (loop)/arch/boot/x86_64/initramfs-linux-cachyos.img
}
Then finally update grub config:
sudo grub-mkconfig -o /boot/grub/grub.cfg
To get the hd1,gpt11 you can go to grub shell and press ls;
Reboot