Cutom tinycore

sudo apt install qemu-utils qemu-system-x86 grub-pc-bin

mkdir tinycore
cd tinycore
wget http://tinycorelinux.net/12.x/x86/release/TinyCore-current.iso

qemu-img create -f qcow2 core-image.img 64M

sudo modprobe nbd max_part=8
sudo qemu-nbd -c /dev/nbd0 core-image.img

sudo mkdir /media/cdrom
sudo mount TinyCore-current.iso /media/cdrom

sudo fdisk /dev/nbd0
n
p
1
enter
enter
p
w

sudo mkfs.ext2 /dev/nbd0p1

sudo mkdir /media/image
sudo mount /dev/nbd0p1 /media/image

sudo mkdir /media/image/boot
sudo mkdir -p /media/image/tce/optional

sudo cp /media/cdrom/boot/core.gz /media/image/boot/
sudo cp /media/cdrom/boot/vmlinuz /media/image/boot/
sudo touch /media/image/tce/onboot.lst

sudo grub-install --boot-directory=/media/image/boot /dev/nbd0

sudo umount /dev/nbd0p1
sudo qemu-nbd -d /dev/nbd0

qemu-system-i386 core-image.img

linux (hd0,msdos1)/boot/vmlinuz
initrd (hd0,msdos1)/boot/core.gz
boot

sudo qemu-nbd -c /dev/nbd0 core-image.img
sudo mount /dev/nbd0p1 /media/image

sudo bash -c "cat <<EOF > /media/image/boot/grub/grub.cfg
set timeout=3
set root='hd0,msdos1'
menuentry 'Boot TinyCore' {
    linux /boot/vmlinuz
    initrd /boot/core.gz
}
EOF"