diff --git a/pkgs/build-support/vm/default.nix b/pkgs/build-support/vm/default.nix
index bcaaa8d7559..700b7778f86 100644
--- a/pkgs/build-support/vm/default.nix
+++ b/pkgs/build-support/vm/default.nix
@@ -162,7 +162,7 @@ rec {
   '';
 
 
-  qemuCommand = ''
+  qemuCommandLinux = ''
     QEMU_SMBD_COMMAND=${samba}/sbin/smbd qemu-system-x86_64 \
       -nographic -no-reboot \
       -smb / -hda $diskImage \
@@ -173,7 +173,7 @@ rec {
   '';
 
   
-  vmRunCommand = writeText "vm-run" ''
+  vmRunCommand = qemuCommand: writeText "vm-run" ''
     export > saved-env
 
     PATH=${coreutils}/bin:${kvm}/bin
@@ -200,6 +200,8 @@ rec {
       exit 1
     fi
     
+    eval "$postVM"
+
     exit $(cat in-vm-exit)
   '';
 
@@ -251,13 +253,62 @@ rec {
      
   runInLinuxVM = attrs: derivation (removeAttrs attrs ["meta" "passthru" "outPath" "drvPath"] // {
     builder = "${bash}/bin/sh";
-    args = ["-e" vmRunCommand];
+    args = ["-e" (vmRunCommand qemuCommandLinux)];
     origArgs = attrs.args;
     origBuilder = attrs.builder;
     QEMU_OPTS = "-m ${toString (if attrs ? memSize then attrs.memSize else 256)}";
   });
 
 
+  qemuCommandGeneric = ''
+    QEMU_SMBD_COMMAND=${samba}/sbin/smbd qemu-system-x86_64 \
+      -nographic -no-reboot \
+      -smb $(pwd) -hda $diskImage \
+      $QEMU_OPTS
+  '';
+
+  
+  /* Run a command in a x86 virtual machine image containing an
+     arbitrary OS.  The VM should be configured to do the following:
+
+     - Write log output to the serial port.
+
+     - Mount //10.0.2.4/qemu via SMB.
+
+     - Execute the command "cmd" on the SMB share.  It can access the
+       original derivation attributes in "saved-env" on the share.
+
+     - Produce output under "out" on the SMB share.
+
+     - Write an exit code to "in-vm-exit" on the SMB share ("0"
+       meaning success).
+
+     - Reboot to shutdown the machine (because Qemu doesn't seem
+       capable of a APM/ACPI VM shutdown).
+  */
+  runInGenericVM = attrs: derivation (removeAttrs attrs ["meta" "passthru" "outPath" "drvPath"] // {
+    system = "i686-linux";
+    builder = "${bash}/bin/sh";
+    args = ["-e" (vmRunCommand qemuCommandGeneric)];
+    QEMU_OPTS = "-m ${toString (if attrs ? memSize then attrs.memSize else 256)}";
+
+    preVM = ''
+      diskImage=$(pwd)/image
+      origImage=${attrs.diskImage}
+      if test -d "$origImage"; then origImage="$origImage/image"; fi
+      qemu-img create -b "$origImage" -f qcow $diskImage
+
+      echo "$buildCommand" > cmd
+
+      eval "$postPreVM"
+    '';
+
+    postVM = ''
+      cp -prvd out $out
+    '';
+  });
+
+
   /* Like runInLinuxVM, but run the build not using the stdenv from
      the Nix store, but using the tools provided by /bin, /usr/bin
      etc. from the specified filesystem image, which typically is a
@@ -357,7 +408,7 @@ rec {
     export origArgs=
     export > $TMPDIR/saved-env
     mountDisk=1
-    ${qemuCommand}
+    ${qemuCommandLinux}
   '';
 
 
diff --git a/pkgs/build-support/vm/test.nix b/pkgs/build-support/vm/test.nix
index b6c3d85d92a..2dce01195b7 100644
--- a/pkgs/build-support/vm/test.nix
+++ b/pkgs/build-support/vm/test.nix
@@ -31,7 +31,40 @@ rec {
       dpkg-query --list
     '';
   });
+
+
+  testFreeBSD = runInGenericVM {
+    name = "aterm-freebsd";
+    src = aterm242fixes.src;
+    diskImage = "/tmp/freebsd-7.0.qcow";
+
+    postPreVM = ''
+      cp $src aterm.tar.bz2
+    '';
+
+    buildCommand = ''
+      set > /tmp/my-env
+      . /mnt/saved-env
+      . /tmp/my-env
+      unset TEMP
+      unset TEMPDIR
+      unset TMP
+      unset TMPDIR
+
+      set -x
+
+      echo "Hello World!!!"
+      mkdir /mnt/out
+      echo "bar" > /mnt/out/foo
+
+      cd /tmp
+      tar xvf /mnt/aterm.tar.bz2
+      cd aterm-*
+      ./configure --prefix=/mnt/out
+      make
+      make install
+    '';
+  };
   
 
-  
 }
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