Ok, this is not about Guix per se

But I understand that in order to play with services you need to run GuixSD in a Qemu virtual machine

I created my virtual machine with this command

guix system vm-image /etc/vm-config-desktop.scm \
   --image-size=30GB \
   --share=$HOME=/exchange

then I copied the image from the store to a local folder
then I run it with this command

qemu-system-x86_64 \
 -net user \
 -net nic,model=virtio \
 -enable-kvm -m 4096 .../projects/qemu-image

Now: I understand that there should be a folder that is shared among the 2 machines, the host and the guest

I can't find it

Where is it ?

Where is iit on the host ?
And where is it on the guest ?

I tried to manually creat /exchhange and put a small text file in it but I couldn't ind it anywhere on the guest

Thanks in advance