diff --git a/lib/backend.py b/lib/backend.py
index 1624c57a5d2ec6f2f97ac1db830683b70c5ce33f..3fda9c7d6febd11ec94ce2c42870d0757b97a502 100644
--- a/lib/backend.py
+++ b/lib/backend.py
@@ -1911,11 +1911,9 @@ def OSFromDisk(name, base_dir=None):
   return payload
 
 
-def OSEnvironment(instance, inst_os, debug=0):
-  """Calculate the environment for an os script.
+def OSCoreEnv(inst_os, debug=0):
+  """Calculate the basic environment for an os script.
 
-  @type instance: L{objects.Instance}
-  @param instance: target instance for the os script run
   @type inst_os: L{objects.OS}
   @param inst_os: operating system for which the environment is being built
   @type debug: integer
@@ -1930,18 +1928,44 @@ def OSEnvironment(instance, inst_os, debug=0):
   api_version = \
     max(constants.OS_API_VERSIONS.intersection(inst_os.api_versions))
   result['OS_API_VERSION'] = '%d' % api_version
-  result['INSTANCE_NAME'] = instance.name
-  result['INSTANCE_OS'] = instance.os
-  result['HYPERVISOR'] = instance.hypervisor
-  result['DISK_COUNT'] = '%d' % len(instance.disks)
-  result['NIC_COUNT'] = '%d' % len(instance.nics)
+  result['OS_NAME'] = inst_os.name
   result['DEBUG_LEVEL'] = '%d' % debug
+
+  # OS variants
   if api_version >= constants.OS_API_V15:
     try:
-      variant = instance.os.split('+', 1)[1]
+      variant = inst_os.name.split('+', 1)[1]
     except IndexError:
       variant = inst_os.supported_variants[0]
     result['OS_VARIANT'] = variant
+
+  return result
+
+
+def OSEnvironment(instance, inst_os, debug=0):
+  """Calculate the environment for an os script.
+
+  @type instance: L{objects.Instance}
+  @param instance: target instance for the os script run
+  @type inst_os: L{objects.OS}
+  @param inst_os: operating system for which the environment is being built
+  @type debug: integer
+  @param debug: debug level (0 or 1, for OS Api 10)
+  @rtype: dict
+  @return: dict of environment variables
+  @raise errors.BlockDeviceError: if the block device
+      cannot be found
+
+  """
+  result = OSCoreEnv(inst_os, debug)
+
+  result['INSTANCE_NAME'] = instance.name
+  result['INSTANCE_OS'] = instance.os
+  result['HYPERVISOR'] = instance.hypervisor
+  result['DISK_COUNT'] = '%d' % len(instance.disks)
+  result['NIC_COUNT'] = '%d' % len(instance.nics)
+
+  # Disks
   for idx, disk in enumerate(instance.disks):
     real_disk = _OpenRealBD(disk)
     result['DISK_%d_PATH' % idx] = real_disk.dev_path
@@ -1954,6 +1978,8 @@ def OSEnvironment(instance, inst_os, debug=0):
     elif disk.dev_type == constants.LD_FILE:
       result['DISK_%d_BACKEND_TYPE' % idx] = \
         'file:%s' % disk.physical_id[0]
+
+  # NICs
   for idx, nic in enumerate(instance.nics):
     result['NIC_%d_MAC' % idx] = nic.mac
     if nic.ip:
@@ -1967,6 +1993,7 @@ def OSEnvironment(instance, inst_os, debug=0):
       result['NIC_%d_FRONTEND_TYPE' % idx] = \
         instance.hvparams[constants.HV_NIC_TYPE]
 
+  # HV/BE params
   for source, kind in [(instance.beparams, "BE"), (instance.hvparams, "HV")]:
     for key, value in source.items():
       result["INSTANCE_%s_%s" % (kind, key)] = str(value)
diff --git a/man/ganeti-os-interface.sgml b/man/ganeti-os-interface.sgml
index e70224f903e3935a3ddff1ab29591fcb42feaf92..2c6ec60446867086bc771221980eccf2b34aabec 100644
--- a/man/ganeti-os-interface.sgml
+++ b/man/ganeti-os-interface.sgml
@@ -86,14 +86,15 @@
         </varlistentry>
         <varlistentry>
           <term>INSTANCE_OS</term>
+          <term>OS_NAME</term>
           <listitem>
-            <simpara>The name of the instance's OS as Ganeti knows
-            it. This can simplify the OS scripts by providing the same
-            scripts under multiple names, and then the scripts can use
-            this name to alter their behaviour.</simpara>
-            <simpara>With OS API 15 changing the script behavior based
-            on this variable is deprecated: OS_VARIANT should be used
-            instead (see below).</simpara>
+            <simpara>Both names point to the name of the instance's OS
+            as Ganeti knows it. This can simplify the OS scripts by
+            providing the same scripts under multiple names, and then
+            the scripts can use this name to alter their
+            behaviour.</simpara> <simpara>With OS API 15 changing the
+            script behavior based on this variable is deprecated:
+            OS_VARIANT should be used instead (see below).</simpara>
           </listitem>
         </varlistentry>
         <varlistentry>