https://fosspost.org/use-qemu-test-operating-systems-distributions

here debian-10.13.0-i386-netinst.iso

prepare disk:

$ qemu-img create  -f raw linux.img 40G

Run installer image with qemu; start new system

$ qemu-system-* -m 1024 -boot d -enable-kvm -smp 3 \
    -net nic -net user -hda linux.img \
    -cdrom debian-10.13.0-i386-netinst.iso

# and install the system ... just do what it takes.
# to run the system just remove the -cdrom option

set up a host-guest bridge for SSH.

# enable a qemu bridge in the config
$ cat /etc/qemu/bridge.conf
allow virbr0

NOTES:

• -f qcow2 format may have better performance.

# install a custom kernel in the “old school way”

The problem is that I can’t build the kernel inside of the virtual machine, I can’t even build it on my host machine (laptop). I need to build the kernel elsewhere (a server) and manually put the kernel img/ramdisk in the guest disk.