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diff --git a/3 Resources/Nix/Nix build vm.md b/3 Resources/Nix/Nix build vm.md
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+---
+tags:
+  - nix
+  - qemu
+---
+`nixos-buildvm` dumps a shell script that:
+
+Creates an empty filesystem image (qcow2) using qemu-img
+
+A qemu KVM VM is started
+```
+exec /nix/store/5v70rrpzv3jwcg7ixa5k9zk0j0lai3nd-qemu-host-cpu-only-9.1.2/bin/qemu-kvm -cpu max \
+    -name tarrel \
+    -m 1024 \
+    -smp 1 \
+    -device virtio-rng-pci \
+    -net nic,netdev=user.0,model=virtio -netdev user,id=user.0,"$QEMU_NET_OPTS" \
+    -virtfs local,path=/nix/store,security_model=none,mount_tag=nix-store \
+    -virtfs local,path="${SHARED_DIR:-$TMPDIR/xchg}",security_model=none,mount_tag=shared \
+    -virtfs local,path="$TMPDIR"/xchg,security_model=none,mount_tag=xchg \
+    -drive cache=writeback,file="$NIX_DISK_IMAGE",id=drive1,if=none,index=1,werror=report -device virtio-blk-pci,bootindex=1,drive=drive1,serial=root \
+    -device virtio-keyboard \
+    -usb \
+    -device usb-tablet,bus=usb-bus.0 \
+    -kernel ${NIXPKGS_QEMU_KERNEL_tarrel:-/nix/store/47zad70cn0qi0pkvv21b43qwiis50lis-nixos-system-tarrel-24.11pre-git/kernel} \
+    -initrd /nix/store/aqbxrnk7jg7piy7g85npm9xysmrvlihw-initrd-linux-6.6.71/initrd \
+    -append "$(cat /nix/store/47zad70cn0qi0pkvv21b43qwiis50lis-nixos-system-tarrel-24.11pre-git/kernel-params) init=/nix/store/47zad70cn0qi0pkvv21b43qwiis50lis-nixos-system-tarrel-24.11pre-git/init regInfo=/nix/store/fii757n9q5f603hmqfdni49lskni93cb-closure-info/registration console=ttyS0,115200n8 console=tty0 $QEMU_KERNEL_PARAMS" \
+    $QEMU_OPTS \
+    "$@"
+```
+
+It shared 3 dirs from the host with the guest most notably the nix store. The disk image is used as a [[Wri]]
+\ No newline at end of file