diff --git a/yocto-poky/scripts/lib/devtool/sdk.py b/yocto-poky/scripts/lib/devtool/sdk.py
index f15a6a9..46fd12b 100644
--- a/yocto-poky/scripts/lib/devtool/sdk.py
+++ b/yocto-poky/scripts/lib/devtool/sdk.py
@@ -1,4 +1,19 @@
 # Development tool - sdk-update command plugin
+#
+# Copyright (C) 2015-2016 Intel Corporation
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
 import os
 import subprocess
@@ -7,14 +22,12 @@
 import shutil
 import errno
 import sys
-from devtool import exec_build_env_command, setup_tinfoil, DevtoolError
+import tempfile
+import re
+from devtool import exec_build_env_command, setup_tinfoil, parse_recipe, DevtoolError
 
 logger = logging.getLogger('devtool')
 
-def plugin_init(pluginlist):
-    """Plugin initialization"""
-    pass
-
 def parse_locked_sigs(sigfile_path):
     """Return <pn:task>:<hash> dictionary"""
     sig_dict = {}
@@ -78,13 +91,26 @@
         logger.debug("Copying %s to %s" % (sb, dst))
         shutil.copy(sb, dst)
 
+def check_manifest(fn, basepath):
+    import bb.utils
+    changedfiles = []
+    with open(fn, 'r') as f:
+        for line in f:
+            splitline = line.split()
+            if len(splitline) > 1:
+                chksum = splitline[0]
+                fpath = splitline[1]
+                curr_chksum = bb.utils.sha256_file(os.path.join(basepath, fpath))
+                if chksum != curr_chksum:
+                    logger.debug('File %s changed: old csum = %s, new = %s' % (os.path.join(basepath, fpath), curr_chksum, chksum))
+                    changedfiles.append(fpath)
+    return changedfiles
+
 def sdk_update(args, config, basepath, workspace):
     # Fetch locked-sigs.inc file from remote/local destination
     updateserver = args.updateserver
     if not updateserver:
         updateserver = config.get('SDK', 'updateserver', '')
-    if not updateserver:
-        raise DevtoolError("Update server not specified in config file, you must specify it on the command line")
     logger.debug("updateserver: %s" % updateserver)
 
     # Make sure we are using sdk-update from within SDK
@@ -101,6 +127,18 @@
     else:
         is_remote = False
 
+    layers_dir = os.path.join(basepath, 'layers')
+    conf_dir = os.path.join(basepath, 'conf')
+
+    # Grab variable values
+    tinfoil = setup_tinfoil(config_only=True, basepath=basepath)
+    try:
+        stamps_dir = tinfoil.config_data.getVar('STAMPS_DIR', True)
+        sstate_mirrors = tinfoil.config_data.getVar('SSTATE_MIRRORS', True)
+        site_conf_version = tinfoil.config_data.getVar('SITE_CONF_VERSION', True)
+    finally:
+        tinfoil.shutdown()
+
     if not is_remote:
         # devtool sdk-update /local/path/to/latest/sdk
         new_locked_sig_file_path = os.path.join(updateserver, 'conf/locked-sigs.inc')
@@ -111,6 +149,7 @@
             logger.debug("Found conf/locked-sigs.inc in %s" % updateserver)
         update_dict = generate_update_dict(new_locked_sig_file_path, old_locked_sig_file_path)
         logger.debug("update_dict = %s" % update_dict)
+        newsdk_path = updateserver
         sstate_dir = os.path.join(newsdk_path, 'sstate-cache')
         if not os.path.exists(sstate_dir):
             logger.error("sstate-cache directory not found under %s" % newsdk_path)
@@ -124,72 +163,204 @@
         install_sstate_objects(sstate_objects, updateserver.rstrip('/'), basepath)
         logger.info("Updating configuration files")
         new_conf_dir = os.path.join(updateserver, 'conf')
-        old_conf_dir = os.path.join(basepath, 'conf')
-        shutil.rmtree(old_conf_dir)
-        shutil.copytree(new_conf_dir, old_conf_dir)
+        shutil.rmtree(conf_dir)
+        shutil.copytree(new_conf_dir, conf_dir)
         logger.info("Updating layers")
         new_layers_dir = os.path.join(updateserver, 'layers')
-        old_layers_dir = os.path.join(basepath, 'layers')
-        shutil.rmtree(old_layers_dir)
-        ret = subprocess.call("cp -a %s %s" % (new_layers_dir, old_layers_dir), shell=True)
+        shutil.rmtree(layers_dir)
+        ret = subprocess.call("cp -a %s %s" % (new_layers_dir, layers_dir), shell=True)
         if ret != 0:
-            logger.error("Copying %s to %s failed" % (new_layers_dir, old_layers_dir))
+            logger.error("Copying %s to %s failed" % (new_layers_dir, layers_dir))
             return ret
     else:
         # devtool sdk-update http://myhost/sdk
-        tmpsdk_dir = '/tmp/sdk-ext'
-        if os.path.exists(tmpsdk_dir):
-            shutil.rmtree(tmpsdk_dir)
-        os.makedirs(tmpsdk_dir)
-        os.makedirs(os.path.join(tmpsdk_dir, 'conf'))
-        # Fetch locked-sigs.inc from update server
-        ret = subprocess.call("wget -q -O - %s/conf/locked-sigs.inc > %s/locked-sigs.inc" % (updateserver, os.path.join(tmpsdk_dir, 'conf')), shell=True)
-        if ret != 0:
-            logger.error("Fetching conf/locked-sigs.inc from %s to %s/locked-sigs.inc failed" % (updateserver, os.path.join(tmpsdk_dir, 'conf')))
-            return ret
-        else:
-            logger.info("Fetching conf/locked-sigs.inc from %s to %s/locked-sigs.inc succeeded" % (updateserver, os.path.join(tmpsdk_dir, 'conf')))
-        new_locked_sig_file_path = os.path.join(tmpsdk_dir, 'conf/locked-sigs.inc')
-        update_dict = generate_update_dict(new_locked_sig_file_path, old_locked_sig_file_path)
-        logger.debug("update_dict = %s" % update_dict)
-        if len(update_dict) == 0:
-            logger.info("No need to update.")
-            return 0
-        # Update metadata
-        logger.debug("Updating meta data via git ...")
-        # Try using 'git pull', if failed, use 'git clone'
-        if os.path.exists(os.path.join(basepath, 'layers/.git')):
-            ret = subprocess.call("cd layers && git pull %s/layers/.git" % updateserver, shell=True)
-        else:
-            ret = -1
-        if ret != 0:
-            ret = subprocess.call("rm -rf layers && git clone %s/layers/.git" % updateserver, shell=True)
-        if ret != 0:
-            logger.error("Updating meta data via git failed")
-            return ret
-        logger.debug("Updating conf files ...")
-        conf_files = ['local.conf', 'bblayers.conf', 'devtool.conf', 'locked-sigs.inc']
-        for conf in conf_files:
-            ret = subprocess.call("wget -q -O - %s/conf/%s > conf/%s" % (updateserver, conf, conf), shell=True)
+        tmpsdk_dir = tempfile.mkdtemp()
+        try:
+            os.makedirs(os.path.join(tmpsdk_dir, 'conf'))
+            new_locked_sig_file_path = os.path.join(tmpsdk_dir, 'conf', 'locked-sigs.inc')
+            # Fetch manifest from server
+            tmpmanifest = os.path.join(tmpsdk_dir, 'conf', 'sdk-conf-manifest')
+            ret = subprocess.call("wget -q -O %s %s/conf/sdk-conf-manifest" % (tmpmanifest, updateserver), shell=True)
+            changedfiles = check_manifest(tmpmanifest, basepath)
+            if not changedfiles:
+                logger.info("Already up-to-date")
+                return 0
+            # Update metadata
+            logger.debug("Updating metadata via git ...")
+            #Check for the status before doing a fetch and reset
+            if os.path.exists(os.path.join(basepath, 'layers/.git')):
+                out = subprocess.check_output("git status --porcelain", shell=True, cwd=layers_dir)
+                if not out:
+                    ret = subprocess.call("git fetch --all; git reset --hard", shell=True, cwd=layers_dir)
+                else:
+                    logger.error("Failed to update metadata as there have been changes made to it. Aborting.");
+                    logger.error("Changed files:\n%s" % out);
+                    return -1
+            else:
+                ret = -1
             if ret != 0:
-                logger.error("Update %s failed" % conf)
-                return ret
-        with open(os.path.join(basepath, 'conf/local.conf'), 'a') as f:
-            f.write('SSTATE_MIRRORS_append = " file://.* %s/sstate-cache/PATH \\n "\n' % updateserver)
+                ret = subprocess.call("git clone %s/layers/.git" % updateserver, shell=True, cwd=tmpsdk_dir)
+                if ret != 0:
+                    logger.error("Updating metadata via git failed")
+                    return ret
+            logger.debug("Updating conf files ...")
+            for changedfile in changedfiles:
+                ret = subprocess.call("wget -q -O %s %s/%s" % (changedfile, updateserver, changedfile), shell=True, cwd=tmpsdk_dir)
+                if ret != 0:
+                    logger.error("Updating %s failed" % changedfile)
+                    return ret
 
-    # Run bitbake command for the whole SDK
-    sdk_targets = config.get('SDK', 'sdk_targets')
-    logger.info("Executing 'bitbake %s' ... (This may take some time.)" % sdk_targets)
-    try:
-        exec_build_env_command(config.init_path, basepath, 'bitbake %s' % sdk_targets)
-    except:
-        logger.error('bitbake %s failed' % sdk_targets)
-        return -1
+            # Check if UNINATIVE_CHECKSUM changed
+            uninative = False
+            if 'conf/local.conf' in changedfiles:
+                def read_uninative_checksums(fn):
+                    chksumitems = []
+                    with open(fn, 'r') as f:
+                        for line in f:
+                            if line.startswith('UNINATIVE_CHECKSUM'):
+                                splitline = re.split(r'[\[\]"\']', line)
+                                if len(splitline) > 3:
+                                    chksumitems.append((splitline[1], splitline[3]))
+                    return chksumitems
+
+                oldsums = read_uninative_checksums(os.path.join(basepath, 'conf/local.conf'))
+                newsums = read_uninative_checksums(os.path.join(tmpsdk_dir, 'conf/local.conf'))
+                if oldsums != newsums:
+                    uninative = True
+                    for buildarch, chksum in newsums:
+                        uninative_file = os.path.join('downloads', 'uninative', chksum, '%s-nativesdk-libc.tar.bz2' % buildarch)
+                        mkdir(os.path.join(tmpsdk_dir, os.path.dirname(uninative_file)))
+                        ret = subprocess.call("wget -q -O %s %s/%s" % (uninative_file, updateserver, uninative_file), shell=True, cwd=tmpsdk_dir)
+
+            # Ok, all is well at this point - move everything over
+            tmplayers_dir = os.path.join(tmpsdk_dir, 'layers')
+            if os.path.exists(tmplayers_dir):
+                shutil.rmtree(layers_dir)
+                shutil.move(tmplayers_dir, layers_dir)
+            for changedfile in changedfiles:
+                destfile = os.path.join(basepath, changedfile)
+                os.remove(destfile)
+                shutil.move(os.path.join(tmpsdk_dir, changedfile), destfile)
+            os.remove(os.path.join(conf_dir, 'sdk-conf-manifest'))
+            shutil.move(tmpmanifest, conf_dir)
+            if uninative:
+                shutil.rmtree(os.path.join(basepath, 'downloads', 'uninative'))
+                shutil.move(os.path.join(tmpsdk_dir, 'downloads', 'uninative'), os.path.join(basepath, 'downloads'))
+
+            if not sstate_mirrors:
+                with open(os.path.join(conf_dir, 'site.conf'), 'a') as f:
+                    f.write('SCONF_VERSION = "%s"\n' % site_conf_version)
+                    f.write('SSTATE_MIRRORS_append = " file://.* %s/sstate-cache/PATH \\n "\n' % updateserver)
+        finally:
+            shutil.rmtree(tmpsdk_dir)
+
+    if not args.skip_prepare:
+        # Find all potentially updateable tasks
+        sdk_update_targets = []
+        tasks = ['do_populate_sysroot', 'do_packagedata']
+        for root, _, files in os.walk(stamps_dir):
+            for fn in files:
+                if not '.sigdata.' in fn:
+                    for task in tasks:
+                        if '.%s.' % task in fn or '.%s_setscene.' % task in fn:
+                            sdk_update_targets.append('%s:%s' % (os.path.basename(root), task))
+        # Run bitbake command for the whole SDK
+        logger.info("Preparing build system... (This may take some time.)")
+        try:
+            exec_build_env_command(config.init_path, basepath, 'bitbake --setscene-only %s' % ' '.join(sdk_update_targets), stderr=subprocess.STDOUT)
+            output, _ = exec_build_env_command(config.init_path, basepath, 'bitbake -n %s' % ' '.join(sdk_update_targets), stderr=subprocess.STDOUT)
+            runlines = []
+            for line in output.splitlines():
+                if 'Running task ' in line:
+                    runlines.append(line)
+            if runlines:
+                logger.error('Unexecuted tasks found in preparation log:\n  %s' % '\n  '.join(runlines))
+                return -1
+        except bb.process.ExecutionError as e:
+            logger.error('Preparation failed:\n%s' % e.stdout)
+            return -1
     return 0
 
+def sdk_install(args, config, basepath, workspace):
+    """Entry point for the devtool sdk-install command"""
+
+    import oe.recipeutils
+    import bb.process
+
+    for recipe in args.recipename:
+        if recipe in workspace:
+            raise DevtoolError('recipe %s is a recipe in your workspace' % recipe)
+
+    tasks = ['do_populate_sysroot', 'do_packagedata']
+    stampprefixes = {}
+    def checkstamp(recipe):
+        stampprefix = stampprefixes[recipe]
+        stamps = glob.glob(stampprefix + '*')
+        for stamp in stamps:
+            if '.sigdata.' not in stamp and stamp.startswith((stampprefix + '.', stampprefix + '_setscene.')):
+                return True
+        else:
+            return False
+
+    install_recipes = []
+    tinfoil = setup_tinfoil(config_only=False, basepath=basepath)
+    try:
+        for recipe in args.recipename:
+            rd = parse_recipe(config, tinfoil, recipe, True)
+            if not rd:
+                return 1
+            stampprefixes[recipe] = '%s.%s' % (rd.getVar('STAMP', True), tasks[0])
+            if checkstamp(recipe):
+                logger.info('%s is already installed' % recipe)
+            else:
+                install_recipes.append(recipe)
+    finally:
+        tinfoil.shutdown()
+
+    if install_recipes:
+        logger.info('Installing %s...' % ', '.join(install_recipes))
+        install_tasks = []
+        for recipe in install_recipes:
+            for task in tasks:
+                if recipe.endswith('-native') and 'package' in task:
+                    continue
+                install_tasks.append('%s:%s' % (recipe, task))
+        options = ''
+        if not args.allow_build:
+            options += ' --setscene-only'
+        try:
+            exec_build_env_command(config.init_path, basepath, 'bitbake %s %s' % (options, ' '.join(install_tasks)), watch=True)
+        except bb.process.ExecutionError as e:
+            raise DevtoolError('Failed to install %s:\n%s' % (recipe, str(e)))
+        failed = False
+        for recipe in install_recipes:
+            if checkstamp(recipe):
+                logger.info('Successfully installed %s' % recipe)
+            else:
+                raise DevtoolError('Failed to install %s - unavailable' % recipe)
+                failed = True
+        if failed:
+            return 2
+
 def register_commands(subparsers, context):
     """Register devtool subcommands from the sdk plugin"""
     if context.fixed_setup:
-        parser_sdk = subparsers.add_parser('sdk-update', help='Update SDK components from a nominated location')
-        parser_sdk.add_argument('updateserver', help='The update server to fetch latest SDK components from', nargs='?')
+        parser_sdk = subparsers.add_parser('sdk-update',
+                                           help='Update SDK components',
+                                           description='Updates installed SDK components from a remote server',
+                                           group='sdk')
+        updateserver = context.config.get('SDK', 'updateserver', '')
+        if updateserver:
+            parser_sdk.add_argument('updateserver', help='The update server to fetch latest SDK components from (default %s)' % updateserver, nargs='?')
+        else:
+            parser_sdk.add_argument('updateserver', help='The update server to fetch latest SDK components from')
+        parser_sdk.add_argument('--skip-prepare', action="store_true", help='Skip re-preparing the build system after updating (for debugging only)')
         parser_sdk.set_defaults(func=sdk_update)
+
+        parser_sdk_install = subparsers.add_parser('sdk-install',
+                                                   help='Install additional SDK components',
+                                                   description='Installs additional recipe development files into the SDK. (You can use "devtool search" to find available recipes.)',
+                                                   group='sdk')
+        parser_sdk_install.add_argument('recipename', help='Name of the recipe to install the development artifacts for', nargs='+')
+        parser_sdk_install.add_argument('-s', '--allow-build', help='Allow building requested item(s) from source', action='store_true')
+        parser_sdk_install.set_defaults(func=sdk_install)