nixpkgs/modules/virtualisation/qemu-vm.nix
Eelco Dolstra 9460a30851 * Use the fileSystems option to mount the host filesystem. Also, it
seems that mount.cifs isn't actually needed (anymore?).

svn path=/nixos/branches/modular-nixos/; revision=16000
2009-06-18 16:47:00 +00:00

67 lines
2.3 KiB
Nix

# This module creates a virtual machine from the NixOS configuration.
# Building the `config.system.build.vm' attribute gives you a command
# that starts a KVM/QEMU VM running the NixOS configuration defined in
# `config'. The Nix store is shared read-only with the host, which
# makes (re)building VMs very efficient. However, it also means you
# can't reconfigure the guest inside the guest - you need to rebuild
# the VM in the host. On the other hand, the root filesystem is a
# read/writable disk image persistent across VM reboots.
{config, pkgs, ...}:
{
# All the modules the initrd needs to mount the host filesystem via
# CIFS. Also use paravirtualised network and block devices for
# performance.
boot.initrd.extraKernelModules =
["cifs" "virtio_net" "virtio_pci" "virtio_blk" "virtio_balloon" "nls_utf8"];
boot.initrd.postDeviceCommands =
''
ipconfig 10.0.2.15:::::eth0:none
'';
# Mount the host filesystem via CIFS, and bind-mount the Nix store
# of the host into our own filesystem.
fileSystems =
[ { mountPoint = "/";
device = "/dev/vda";
}
{ mountPoint = "/hostfs";
device = "//10.0.2.4/qemu";
fsType = "cifs";
options = "guest,username=nobody";
neededForBoot = true;
}
{ mountPoint = "/nix/store";
device = "/hostfs/nix/store";
options = "bind";
neededForBoot = true;
}
];
# Starting DHCP brings down eth0, which kills the connection to the
# host filesystem and thus deadlocks the system.
networking.useDHCP = false;
system.build.vm = pkgs.runCommand "nixos-vm" {}
''
ensureDir $out
ln -s ${config.system.build.system} $out/system
ensureDir $out/bin
cat > $out/bin/run-nixos-vm <<EOF
#! ${pkgs.stdenv.shell}
export PATH=${pkgs.samba}/sbin:\$PATH
${pkgs.kvm}/bin/qemu-system-x86_64 \
-net nic,model=virtio -net user -smb / \
-drive file=\$diskImage,if=virtio,boot=on \
-kernel ${config.system.build.system}/kernel \
-initrd ${config.system.build.system}/initrd \
-append "\$(cat ${config.system.build.system}/kernel-params) init=${config.system.build.bootStage2} systemConfig=${config.system.build.system}"
EOF
chmod u+x $out/bin/run-nixos-vm
'';
}