diff --git a/poky/bitbake/lib/bb/__init__.py b/poky/bitbake/lib/bb/__init__.py
index 09e161f..b217737 100644
--- a/poky/bitbake/lib/bb/__init__.py
+++ b/poky/bitbake/lib/bb/__init__.py
@@ -9,7 +9,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 #
 
-__version__ = "1.48.0"
+__version__ = "1.49.0"
 
 import sys
 if sys.version_info < (3, 5, 0):
diff --git a/poky/bitbake/lib/bb/cache.py b/poky/bitbake/lib/bb/cache.py
index 9e0c931..b8054e0 100644
--- a/poky/bitbake/lib/bb/cache.py
+++ b/poky/bitbake/lib/bb/cache.py
@@ -449,9 +449,7 @@
         return cachesize
 
     def load_cachefile(self, progress):
-        cachesize = self.cachesize()
         previous_progress = 0
-        previous_percent = 0
 
         for cache_class in self.caches_array:
             cachefile = self.getCacheFile(cache_class.cachefile)
@@ -816,10 +814,6 @@
         for k in self.__caches:
             yield k
 
-    def keys(self):
-        return self.__caches[key]
-
-
 def init(cooker):
     """
     The Objective: Cache the minimum amount of data possible yet get to the
diff --git a/poky/bitbake/lib/bb/cookerdata.py b/poky/bitbake/lib/bb/cookerdata.py
index 91cc434..c39b568 100644
--- a/poky/bitbake/lib/bb/cookerdata.py
+++ b/poky/bitbake/lib/bb/cookerdata.py
@@ -23,8 +23,8 @@
 parselog    = logging.getLogger("BitBake.Parsing")
 
 class ConfigParameters(object):
-    def __init__(self, argv=sys.argv):
-        self.options, targets = self.parseCommandLine(argv)
+    def __init__(self, argv=None):
+        self.options, targets = self.parseCommandLine(argv or sys.argv)
         self.environment = self.parseEnvironment()
 
         self.options.pkgs_to_build = targets or []
@@ -209,7 +209,7 @@
     return None
 
 #
-# We search for a conf/bblayers.conf under an entry in BBPATH or in cwd working 
+# We search for a conf/bblayers.conf under an entry in BBPATH or in cwd working
 # up to /. If that fails, we search for a conf/bitbake.conf in BBPATH.
 #
 
diff --git a/poky/bitbake/lib/bb/fetch2/__init__.py b/poky/bitbake/lib/bb/fetch2/__init__.py
index 551bfb7..2907730 100644
--- a/poky/bitbake/lib/bb/fetch2/__init__.py
+++ b/poky/bitbake/lib/bb/fetch2/__init__.py
@@ -853,11 +853,6 @@
         if val:
             cmd = 'export ' + var + '=\"%s\"; %s' % (val, cmd)
 
-    # Ensure that a _PYTHON_SYSCONFIGDATA_NAME value set by a recipe
-    # (for example via python3native.bbclass since warrior) is not set for
-    # host Python (otherwise tools like git-make-shallow will fail)
-    cmd = 'unset _PYTHON_SYSCONFIGDATA_NAME; ' + cmd
-
     # Disable pseudo as it may affect ssh, potentially causing it to hang.
     cmd = 'export PSEUDO_DISABLED=1; ' + cmd
 
@@ -1026,7 +1021,8 @@
                     origud.method.build_mirror_data(origud, ld)
             return origud.localpath
         # Otherwise the result is a local file:// and we symlink to it
-        ensure_symlink(ud.localpath, origud.localpath)
+        ensure_symlink(ud.localpath, origud.localpath, relative=True)
+
         update_stamp(origud, ld)
         return ud.localpath
 
@@ -1060,7 +1056,7 @@
             bb.utils.unlockfile(lf)
 
 
-def ensure_symlink(target, link_name):
+def ensure_symlink(target, link_name, relative=False):
     if not os.path.exists(link_name):
         if os.path.islink(link_name):
             # Broken symbolic link
@@ -1071,6 +1067,8 @@
         # same time, in which case we do not want the second task to
         # fail when the link has already been created by the first task.
         try:
+            if relative is True:
+                target = os.path.relpath(target, os.path.dirname(link_name))
             os.symlink(target, link_name)
         except FileExistsError:
             pass
@@ -1461,6 +1459,10 @@
                 cmd = '7z x -so %s | tar x --no-same-owner -f -' % file
             elif file.endswith('.7z'):
                 cmd = '7za x -y %s 1>/dev/null' % file
+            elif file.endswith('.tzst') or file.endswith('.tar.zst'):
+                cmd = 'zstd --decompress --stdout %s | tar x --no-same-owner -f -' % file
+            elif file.endswith('.zst'):
+                cmd = 'zstd --decompress --stdout %s > %s' % (file, efile)
             elif file.endswith('.zip') or file.endswith('.jar'):
                 try:
                     dos = bb.utils.to_boolean(urldata.parm.get('dos'), False)
diff --git a/poky/bitbake/lib/bb/fetch2/git.py b/poky/bitbake/lib/bb/fetch2/git.py
index b97967b..490d57f 100644
--- a/poky/bitbake/lib/bb/fetch2/git.py
+++ b/poky/bitbake/lib/bb/fetch2/git.py
@@ -595,6 +595,11 @@
         """
         Return the repository URL
         """
+        # Note that we do not support passwords directly in the git urls. There are several
+        # reasons. SRC_URI can be written out to things like buildhistory and people don't
+        # want to leak passwords like that. Its also all too easy to share metadata without 
+        # removing the password. ssh keys, ~/.netrc and ~/.ssh/config files can be used as
+        # alternatives so we will not take patches adding password support here.
         if ud.user:
             username = ud.user + '@'
         else:
diff --git a/poky/bitbake/lib/bb/main.py b/poky/bitbake/lib/bb/main.py
index e92e409..06bad49 100755
--- a/poky/bitbake/lib/bb/main.py
+++ b/poky/bitbake/lib/bb/main.py
@@ -119,178 +119,181 @@
 warnings.filterwarnings("ignore", category=DeprecationWarning, module="<string>$")
 warnings.filterwarnings("ignore", message="With-statements now directly support multiple context managers")
 
-class BitBakeConfigParameters(cookerdata.ConfigParameters):
 
-    def parseCommandLine(self, argv=sys.argv):
-        parser = optparse.OptionParser(
-            formatter=BitbakeHelpFormatter(),
-            version="BitBake Build Tool Core version %s" % bb.__version__,
-            usage="""%prog [options] [recipename/target recipe:do_task ...]
+def create_bitbake_parser():
+    parser = optparse.OptionParser(
+        formatter=BitbakeHelpFormatter(),
+        version="BitBake Build Tool Core version %s" % bb.__version__,
+        usage="""%prog [options] [recipename/target recipe:do_task ...]
 
     Executes the specified task (default is 'build') for a given set of target recipes (.bb files).
     It is assumed there is a conf/bblayers.conf available in cwd or in BBPATH which
     will provide the layer, BBFILES and other configuration information.""")
 
-        parser.add_option("-b", "--buildfile", action="store", dest="buildfile", default=None,
-                          help="Execute tasks from a specific .bb recipe directly. WARNING: Does "
-                               "not handle any dependencies from other recipes.")
+    parser.add_option("-b", "--buildfile", action="store", dest="buildfile", default=None,
+                      help="Execute tasks from a specific .bb recipe directly. WARNING: Does "
+                           "not handle any dependencies from other recipes.")
 
-        parser.add_option("-k", "--continue", action="store_false", dest="abort", default=True,
-                          help="Continue as much as possible after an error. While the target that "
-                               "failed and anything depending on it cannot be built, as much as "
-                               "possible will be built before stopping.")
+    parser.add_option("-k", "--continue", action="store_false", dest="abort", default=True,
+                      help="Continue as much as possible after an error. While the target that "
+                           "failed and anything depending on it cannot be built, as much as "
+                           "possible will be built before stopping.")
 
-        parser.add_option("-f", "--force", action="store_true", dest="force", default=False,
-                          help="Force the specified targets/task to run (invalidating any "
-                               "existing stamp file).")
+    parser.add_option("-f", "--force", action="store_true", dest="force", default=False,
+                      help="Force the specified targets/task to run (invalidating any "
+                           "existing stamp file).")
 
-        parser.add_option("-c", "--cmd", action="store", dest="cmd",
-                          help="Specify the task to execute. The exact options available "
-                               "depend on the metadata. Some examples might be 'compile'"
-                               " or 'populate_sysroot' or 'listtasks' may give a list of "
-                               "the tasks available.")
+    parser.add_option("-c", "--cmd", action="store", dest="cmd",
+                      help="Specify the task to execute. The exact options available "
+                           "depend on the metadata. Some examples might be 'compile'"
+                           " or 'populate_sysroot' or 'listtasks' may give a list of "
+                           "the tasks available.")
 
-        parser.add_option("-C", "--clear-stamp", action="store", dest="invalidate_stamp",
-                          help="Invalidate the stamp for the specified task such as 'compile' "
-                               "and then run the default task for the specified target(s).")
+    parser.add_option("-C", "--clear-stamp", action="store", dest="invalidate_stamp",
+                      help="Invalidate the stamp for the specified task such as 'compile' "
+                           "and then run the default task for the specified target(s).")
 
-        parser.add_option("-r", "--read", action="append", dest="prefile", default=[],
-                          help="Read the specified file before bitbake.conf.")
+    parser.add_option("-r", "--read", action="append", dest="prefile", default=[],
+                      help="Read the specified file before bitbake.conf.")
 
-        parser.add_option("-R", "--postread", action="append", dest="postfile", default=[],
-                          help="Read the specified file after bitbake.conf.")
+    parser.add_option("-R", "--postread", action="append", dest="postfile", default=[],
+                      help="Read the specified file after bitbake.conf.")
 
-        parser.add_option("-v", "--verbose", action="store_true", dest="verbose", default=False,
-                          help="Enable tracing of shell tasks (with 'set -x'). "
-                               "Also print bb.note(...) messages to stdout (in "
-                               "addition to writing them to ${T}/log.do_<task>).")
+    parser.add_option("-v", "--verbose", action="store_true", dest="verbose", default=False,
+                      help="Enable tracing of shell tasks (with 'set -x'). "
+                           "Also print bb.note(...) messages to stdout (in "
+                           "addition to writing them to ${T}/log.do_<task>).")
 
-        parser.add_option("-D", "--debug", action="count", dest="debug", default=0,
-                          help="Increase the debug level. You can specify this "
-                               "more than once. -D sets the debug level to 1, "
-                               "where only bb.debug(1, ...) messages are printed "
-                               "to stdout; -DD sets the debug level to 2, where "
-                               "both bb.debug(1, ...) and bb.debug(2, ...) "
-                               "messages are printed; etc. Without -D, no debug "
-                               "messages are printed. Note that -D only affects "
-                               "output to stdout. All debug messages are written "
-                               "to ${T}/log.do_taskname, regardless of the debug "
-                               "level.")
+    parser.add_option("-D", "--debug", action="count", dest="debug", default=0,
+                      help="Increase the debug level. You can specify this "
+                           "more than once. -D sets the debug level to 1, "
+                           "where only bb.debug(1, ...) messages are printed "
+                           "to stdout; -DD sets the debug level to 2, where "
+                           "both bb.debug(1, ...) and bb.debug(2, ...) "
+                           "messages are printed; etc. Without -D, no debug "
+                           "messages are printed. Note that -D only affects "
+                           "output to stdout. All debug messages are written "
+                           "to ${T}/log.do_taskname, regardless of the debug "
+                           "level.")
 
-        parser.add_option("-q", "--quiet", action="count", dest="quiet", default=0,
-                          help="Output less log message data to the terminal. You can specify this more than once.")
+    parser.add_option("-q", "--quiet", action="count", dest="quiet", default=0,
+                      help="Output less log message data to the terminal. You can specify this more than once.")
 
-        parser.add_option("-n", "--dry-run", action="store_true", dest="dry_run", default=False,
-                          help="Don't execute, just go through the motions.")
+    parser.add_option("-n", "--dry-run", action="store_true", dest="dry_run", default=False,
+                      help="Don't execute, just go through the motions.")
 
-        parser.add_option("-S", "--dump-signatures", action="append", dest="dump_signatures",
-                          default=[], metavar="SIGNATURE_HANDLER",
-                          help="Dump out the signature construction information, with no task "
-                               "execution. The SIGNATURE_HANDLER parameter is passed to the "
-                               "handler. Two common values are none and printdiff but the handler "
-                               "may define more/less. none means only dump the signature, printdiff"
-                               " means compare the dumped signature with the cached one.")
+    parser.add_option("-S", "--dump-signatures", action="append", dest="dump_signatures",
+                      default=[], metavar="SIGNATURE_HANDLER",
+                      help="Dump out the signature construction information, with no task "
+                           "execution. The SIGNATURE_HANDLER parameter is passed to the "
+                           "handler. Two common values are none and printdiff but the handler "
+                           "may define more/less. none means only dump the signature, printdiff"
+                           " means compare the dumped signature with the cached one.")
 
-        parser.add_option("-p", "--parse-only", action="store_true",
-                          dest="parse_only", default=False,
-                          help="Quit after parsing the BB recipes.")
+    parser.add_option("-p", "--parse-only", action="store_true",
+                      dest="parse_only", default=False,
+                      help="Quit after parsing the BB recipes.")
 
-        parser.add_option("-s", "--show-versions", action="store_true",
-                          dest="show_versions", default=False,
-                          help="Show current and preferred versions of all recipes.")
+    parser.add_option("-s", "--show-versions", action="store_true",
+                      dest="show_versions", default=False,
+                      help="Show current and preferred versions of all recipes.")
 
-        parser.add_option("-e", "--environment", action="store_true",
-                          dest="show_environment", default=False,
-                          help="Show the global or per-recipe environment complete with information"
-                               " about where variables were set/changed.")
+    parser.add_option("-e", "--environment", action="store_true",
+                      dest="show_environment", default=False,
+                      help="Show the global or per-recipe environment complete with information"
+                           " about where variables were set/changed.")
 
-        parser.add_option("-g", "--graphviz", action="store_true", dest="dot_graph", default=False,
-                          help="Save dependency tree information for the specified "
-                               "targets in the dot syntax.")
+    parser.add_option("-g", "--graphviz", action="store_true", dest="dot_graph", default=False,
+                      help="Save dependency tree information for the specified "
+                           "targets in the dot syntax.")
 
-        parser.add_option("-I", "--ignore-deps", action="append",
-                          dest="extra_assume_provided", default=[],
-                          help="Assume these dependencies don't exist and are already provided "
-                               "(equivalent to ASSUME_PROVIDED). Useful to make dependency "
-                               "graphs more appealing")
+    parser.add_option("-I", "--ignore-deps", action="append",
+                      dest="extra_assume_provided", default=[],
+                      help="Assume these dependencies don't exist and are already provided "
+                           "(equivalent to ASSUME_PROVIDED). Useful to make dependency "
+                           "graphs more appealing")
 
-        parser.add_option("-l", "--log-domains", action="append", dest="debug_domains", default=[],
-                          help="Show debug logging for the specified logging domains")
+    parser.add_option("-l", "--log-domains", action="append", dest="debug_domains", default=[],
+                      help="Show debug logging for the specified logging domains")
 
-        parser.add_option("-P", "--profile", action="store_true", dest="profile", default=False,
-                          help="Profile the command and save reports.")
+    parser.add_option("-P", "--profile", action="store_true", dest="profile", default=False,
+                      help="Profile the command and save reports.")
 
-        # @CHOICES@ is substituted out by BitbakeHelpFormatter above
-        parser.add_option("-u", "--ui", action="store", dest="ui",
-                          default=os.environ.get('BITBAKE_UI', 'knotty'),
-                          help="The user interface to use (@CHOICES@ - default %default).")
+    # @CHOICES@ is substituted out by BitbakeHelpFormatter above
+    parser.add_option("-u", "--ui", action="store", dest="ui",
+                      default=os.environ.get('BITBAKE_UI', 'knotty'),
+                      help="The user interface to use (@CHOICES@ - default %default).")
 
-        parser.add_option("", "--token", action="store", dest="xmlrpctoken",
-                          default=os.environ.get("BBTOKEN"),
-                          help="Specify the connection token to be used when connecting "
-                               "to a remote server.")
+    parser.add_option("", "--token", action="store", dest="xmlrpctoken",
+                      default=os.environ.get("BBTOKEN"),
+                      help="Specify the connection token to be used when connecting "
+                           "to a remote server.")
 
-        parser.add_option("", "--revisions-changed", action="store_true",
-                          dest="revisions_changed", default=False,
-                          help="Set the exit code depending on whether upstream floating "
-                               "revisions have changed or not.")
+    parser.add_option("", "--revisions-changed", action="store_true",
+                      dest="revisions_changed", default=False,
+                      help="Set the exit code depending on whether upstream floating "
+                           "revisions have changed or not.")
 
-        parser.add_option("", "--server-only", action="store_true",
-                          dest="server_only", default=False,
-                          help="Run bitbake without a UI, only starting a server "
-                               "(cooker) process.")
+    parser.add_option("", "--server-only", action="store_true",
+                      dest="server_only", default=False,
+                      help="Run bitbake without a UI, only starting a server "
+                           "(cooker) process.")
 
-        parser.add_option("-B", "--bind", action="store", dest="bind", default=False,
-                          help="The name/address for the bitbake xmlrpc server to bind to.")
+    parser.add_option("-B", "--bind", action="store", dest="bind", default=False,
+                      help="The name/address for the bitbake xmlrpc server to bind to.")
 
-        parser.add_option("-T", "--idle-timeout", type=float, dest="server_timeout",
-                          default=os.getenv("BB_SERVER_TIMEOUT"),
-                          help="Set timeout to unload bitbake server due to inactivity, "
-                                "set to -1 means no unload, "
-                                "default: Environment variable BB_SERVER_TIMEOUT.")
+    parser.add_option("-T", "--idle-timeout", type=float, dest="server_timeout",
+                      default=os.getenv("BB_SERVER_TIMEOUT"),
+                      help="Set timeout to unload bitbake server due to inactivity, "
+                           "set to -1 means no unload, "
+                           "default: Environment variable BB_SERVER_TIMEOUT.")
 
-        parser.add_option("", "--no-setscene", action="store_true",
-                          dest="nosetscene", default=False,
-                          help="Do not run any setscene tasks. sstate will be ignored and "
-                               "everything needed, built.")
+    parser.add_option("", "--no-setscene", action="store_true",
+                      dest="nosetscene", default=False,
+                      help="Do not run any setscene tasks. sstate will be ignored and "
+                           "everything needed, built.")
 
-        parser.add_option("", "--skip-setscene", action="store_true",
-                          dest="skipsetscene", default=False,
-                          help="Skip setscene tasks if they would be executed. Tasks previously "
-                               "restored from sstate will be kept, unlike --no-setscene")
+    parser.add_option("", "--skip-setscene", action="store_true",
+                      dest="skipsetscene", default=False,
+                      help="Skip setscene tasks if they would be executed. Tasks previously "
+                           "restored from sstate will be kept, unlike --no-setscene")
 
-        parser.add_option("", "--setscene-only", action="store_true",
-                          dest="setsceneonly", default=False,
-                          help="Only run setscene tasks, don't run any real tasks.")
+    parser.add_option("", "--setscene-only", action="store_true",
+                      dest="setsceneonly", default=False,
+                      help="Only run setscene tasks, don't run any real tasks.")
 
-        parser.add_option("", "--remote-server", action="store", dest="remote_server",
-                          default=os.environ.get("BBSERVER"),
-                          help="Connect to the specified server.")
+    parser.add_option("", "--remote-server", action="store", dest="remote_server",
+                      default=os.environ.get("BBSERVER"),
+                      help="Connect to the specified server.")
 
-        parser.add_option("-m", "--kill-server", action="store_true",
-                          dest="kill_server", default=False,
-                          help="Terminate any running bitbake server.")
+    parser.add_option("-m", "--kill-server", action="store_true",
+                      dest="kill_server", default=False,
+                      help="Terminate any running bitbake server.")
 
-        parser.add_option("", "--observe-only", action="store_true",
-                          dest="observe_only", default=False,
-                          help="Connect to a server as an observing-only client.")
+    parser.add_option("", "--observe-only", action="store_true",
+                      dest="observe_only", default=False,
+                      help="Connect to a server as an observing-only client.")
 
-        parser.add_option("", "--status-only", action="store_true",
-                          dest="status_only", default=False,
-                          help="Check the status of the remote bitbake server.")
+    parser.add_option("", "--status-only", action="store_true",
+                      dest="status_only", default=False,
+                      help="Check the status of the remote bitbake server.")
 
-        parser.add_option("-w", "--write-log", action="store", dest="writeeventlog",
-                          default=os.environ.get("BBEVENTLOG"),
-                          help="Writes the event log of the build to a bitbake event json file. "
-                               "Use '' (empty string) to assign the name automatically.")
+    parser.add_option("-w", "--write-log", action="store", dest="writeeventlog",
+                      default=os.environ.get("BBEVENTLOG"),
+                      help="Writes the event log of the build to a bitbake event json file. "
+                           "Use '' (empty string) to assign the name automatically.")
 
-        parser.add_option("", "--runall", action="append", dest="runall",
-                          help="Run the specified task for any recipe in the taskgraph of the specified target (even if it wouldn't otherwise have run).")
+    parser.add_option("", "--runall", action="append", dest="runall",
+                      help="Run the specified task for any recipe in the taskgraph of the specified target (even if it wouldn't otherwise have run).")
 
-        parser.add_option("", "--runonly", action="append", dest="runonly",
-                          help="Run only the specified task within the taskgraph of the specified targets (and any task dependencies those tasks may have).")
+    parser.add_option("", "--runonly", action="append", dest="runonly",
+                      help="Run only the specified task within the taskgraph of the specified targets (and any task dependencies those tasks may have).")
+    return parser
 
 
+class BitBakeConfigParameters(cookerdata.ConfigParameters):
+    def parseCommandLine(self, argv=sys.argv):
+        parser = create_bitbake_parser()
         options, targets = parser.parse_args(argv)
 
         if options.quiet and options.verbose:
@@ -466,7 +469,7 @@
                     logger.info("Retrying server connection (#%d)..." % tryno)
                 else:
                     logger.info("Retrying server connection (#%d)... (%s)" % (tryno, traceback.format_exc()))
-                
+
             if not retries:
                 bb.fatal("Unable to connect to bitbake server, or start one (server startup failures would be in bitbake-cookerdaemon.log).")
             bb.event.print_ui_queue()
diff --git a/poky/bitbake/lib/bb/monitordisk.py b/poky/bitbake/lib/bb/monitordisk.py
index e7c0726..98f2109 100644
--- a/poky/bitbake/lib/bb/monitordisk.py
+++ b/poky/bitbake/lib/bb/monitordisk.py
@@ -59,7 +59,7 @@
         pass
     return None
 
-def getDiskData(BBDirs, configuration):
+def getDiskData(BBDirs):
 
     """Prepare disk data for disk space monitor"""
 
@@ -168,7 +168,7 @@
 
         BBDirs = configuration.getVar("BB_DISKMON_DIRS") or None
         if BBDirs:
-            self.devDict = getDiskData(BBDirs, configuration)
+            self.devDict = getDiskData(BBDirs)
             if self.devDict:
                 self.spaceInterval, self.inodeInterval = getInterval(configuration)
                 if self.spaceInterval and self.inodeInterval:
diff --git a/poky/bitbake/lib/bb/parse/parse_py/BBHandler.py b/poky/bitbake/lib/bb/parse/parse_py/BBHandler.py
index 215f940..8a520e3 100644
--- a/poky/bitbake/lib/bb/parse/parse_py/BBHandler.py
+++ b/poky/bitbake/lib/bb/parse/parse_py/BBHandler.py
@@ -13,7 +13,7 @@
 #
 
 import re, bb, os
-import bb.build, bb.utils
+import bb.build, bb.utils, bb.data_smart
 
 from . import ConfHandler
 from .. import resolve_file, ast, logger, ParseError
@@ -233,6 +233,10 @@
             if taskexpression.count(word) > 1:
                 logger.warning("addtask contained multiple '%s' keywords, only one is supported" % word)
 
+        # Check and warn for having task with exprssion as part of task name
+        for te in taskexpression:
+            if any( ( "%s_" % keyword ) in te for keyword in bb.data_smart.__setvar_keyword__ ):
+                raise ParseError("Task name '%s' contains a keyword which is not recommended/supported.\nPlease rename the task not to include the keyword.\n%s" % (te, ("\n".join(map(str, bb.data_smart.__setvar_keyword__)))), fn)
         ast.handleAddTask(statements, fn, lineno, m)
         return
 
diff --git a/poky/bitbake/lib/bb/providers.py b/poky/bitbake/lib/bb/providers.py
index 81459c3..3f66a3d 100644
--- a/poky/bitbake/lib/bb/providers.py
+++ b/poky/bitbake/lib/bb/providers.py
@@ -151,7 +151,7 @@
         if item:
             itemstr = " (for item %s)" % item
         if preferred_file is None:
-            logger.info("preferred version %s of %s not available%s", pv_str, pn, itemstr)
+            logger.warn("preferred version %s of %s not available%s", pv_str, pn, itemstr)
             available_vers = []
             for file_set in pkg_pn:
                 for f in file_set:
@@ -163,7 +163,7 @@
                         available_vers.append(ver_str)
             if available_vers:
                 available_vers.sort()
-                logger.info("versions of %s available: %s", pn, ' '.join(available_vers))
+                logger.warn("versions of %s available: %s", pn, ' '.join(available_vers))
         else:
             logger.debug(1, "selecting %s as PREFERRED_VERSION %s of package %s%s", preferred_file, pv_str, pn, itemstr)
 
diff --git a/poky/bitbake/lib/bb/siggen.py b/poky/bitbake/lib/bb/siggen.py
index 86e0e16..0ac3952 100644
--- a/poky/bitbake/lib/bb/siggen.py
+++ b/poky/bitbake/lib/bb/siggen.py
@@ -311,13 +311,7 @@
 
         data = self.basehash[tid]
         for dep in self.runtaskdeps[tid]:
-            if dep in self.unihash:
-                if self.unihash[dep] is None:
-                    data = data + self.taskhash[dep]
-                else:
-                    data = data + self.unihash[dep]
-            else:
-                data = data + self.get_unihash(dep)
+            data = data + self.get_unihash(dep)
 
         for (f, cs) in self.file_checksum_values[tid]:
             if cs:
diff --git a/poky/bitbake/lib/hashserv/__init__.py b/poky/bitbake/lib/hashserv/__init__.py
index f95e8f4..55f4841 100644
--- a/poky/bitbake/lib/hashserv/__init__.py
+++ b/poky/bitbake/lib/hashserv/__init__.py
@@ -3,6 +3,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 #
 
+import asyncio
 from contextlib import closing
 import re
 import sqlite3
@@ -21,6 +22,24 @@
 # is necessary
 DEFAULT_MAX_CHUNK = 32 * 1024
 
+TABLE_DEFINITION = (
+    ("method", "TEXT NOT NULL"),
+    ("outhash", "TEXT NOT NULL"),
+    ("taskhash", "TEXT NOT NULL"),
+    ("unihash", "TEXT NOT NULL"),
+    ("created", "DATETIME"),
+
+    # Optional fields
+    ("owner", "TEXT"),
+    ("PN", "TEXT"),
+    ("PV", "TEXT"),
+    ("PR", "TEXT"),
+    ("task", "TEXT"),
+    ("outhash_siginfo", "TEXT"),
+)
+
+TABLE_COLUMNS = tuple(name for name, _ in TABLE_DEFINITION)
+
 def setup_database(database, sync=True):
     db = sqlite3.connect(database)
     db.row_factory = sqlite3.Row
@@ -29,23 +48,10 @@
         cursor.execute('''
             CREATE TABLE IF NOT EXISTS tasks_v2 (
                 id INTEGER PRIMARY KEY AUTOINCREMENT,
-                method TEXT NOT NULL,
-                outhash TEXT NOT NULL,
-                taskhash TEXT NOT NULL,
-                unihash TEXT NOT NULL,
-                created DATETIME,
-
-                -- Optional fields
-                owner TEXT,
-                PN TEXT,
-                PV TEXT,
-                PR TEXT,
-                task TEXT,
-                outhash_siginfo TEXT,
-
+                %s
                 UNIQUE(method, outhash, taskhash)
                 )
-            ''')
+            ''' % " ".join("%s %s," % (name, typ) for name, typ in TABLE_DEFINITION))
         cursor.execute('PRAGMA journal_mode = WAL')
         cursor.execute('PRAGMA synchronous = %s' % ('NORMAL' if sync else 'OFF'))
 
@@ -88,10 +94,10 @@
         yield "\n"
 
 
-def create_server(addr, dbname, *, sync=True):
+def create_server(addr, dbname, *, sync=True, upstream=None):
     from . import server
     db = setup_database(dbname, sync=sync)
-    s = server.Server(db)
+    s = server.Server(db, upstream=upstream)
 
     (typ, a) = parse_address(addr)
     if typ == ADDR_TYPE_UNIX:
@@ -113,3 +119,15 @@
         c.connect_tcp(*a)
 
     return c
+
+async def create_async_client(addr):
+    from . import client
+    c = client.AsyncClient()
+
+    (typ, a) = parse_address(addr)
+    if typ == ADDR_TYPE_UNIX:
+        await c.connect_unix(*a)
+    else:
+        await c.connect_tcp(*a)
+
+    return c
diff --git a/poky/bitbake/lib/hashserv/client.py b/poky/bitbake/lib/hashserv/client.py
index a29af83..ae5875d 100644
--- a/poky/bitbake/lib/hashserv/client.py
+++ b/poky/bitbake/lib/hashserv/client.py
@@ -3,189 +3,216 @@
 # SPDX-License-Identifier: GPL-2.0-only
 #
 
+import asyncio
 import json
 import logging
 import socket
 import os
-from . import chunkify, DEFAULT_MAX_CHUNK
+from . import chunkify, DEFAULT_MAX_CHUNK, create_async_client
 
 
-logger = logging.getLogger('hashserv.client')
+logger = logging.getLogger("hashserv.client")
 
 
 class HashConnectionError(Exception):
     pass
 
 
-class Client(object):
+class AsyncClient(object):
     MODE_NORMAL = 0
     MODE_GET_STREAM = 1
 
     def __init__(self):
-        self._socket = None
         self.reader = None
         self.writer = None
         self.mode = self.MODE_NORMAL
         self.max_chunk = DEFAULT_MAX_CHUNK
 
-    def connect_tcp(self, address, port):
-        def connect_sock():
-            s = socket.create_connection((address, port))
-
-            s.setsockopt(socket.SOL_TCP, socket.TCP_NODELAY, 1)
-            s.setsockopt(socket.SOL_TCP, socket.TCP_QUICKACK, 1)
-            s.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
-            return s
+    async def connect_tcp(self, address, port):
+        async def connect_sock():
+            return await asyncio.open_connection(address, port)
 
         self._connect_sock = connect_sock
 
-    def connect_unix(self, path):
-        def connect_sock():
-            s = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-            # AF_UNIX has path length issues so chdir here to workaround
-            cwd = os.getcwd()
-            try:
-                os.chdir(os.path.dirname(path))
-                s.connect(os.path.basename(path))
-            finally:
-                os.chdir(cwd)
-            return s
+    async def connect_unix(self, path):
+        async def connect_sock():
+            return await asyncio.open_unix_connection(path)
 
         self._connect_sock = connect_sock
 
-    def connect(self):
-        if self._socket is None:
-            self._socket = self._connect_sock()
+    async def _connect(self):
+        if self.reader is None or self.writer is None:
+            (self.reader, self.writer) = await self._connect_sock()
 
-            self.reader = self._socket.makefile('r', encoding='utf-8')
-            self.writer = self._socket.makefile('w', encoding='utf-8')
+            self.writer.write("OEHASHEQUIV 1.1\n\n".encode("utf-8"))
+            await self.writer.drain()
 
-            self.writer.write('OEHASHEQUIV 1.1\n\n')
-            self.writer.flush()
-
-            # Restore mode if the socket is being re-created
             cur_mode = self.mode
             self.mode = self.MODE_NORMAL
-            self._set_mode(cur_mode)
+            await self._set_mode(cur_mode)
 
-        return self._socket
+    async def close(self):
+        self.reader = None
 
-    def close(self):
-        if self._socket is not None:
-            self._socket.close()
-            self._socket = None
-            self.reader = None
+        if self.writer is not None:
+            self.writer.close()
             self.writer = None
 
-    def _send_wrapper(self, proc):
+    async def _send_wrapper(self, proc):
         count = 0
         while True:
             try:
-                self.connect()
-                return proc()
-            except (OSError, HashConnectionError, json.JSONDecodeError, UnicodeDecodeError) as e:
-                logger.warning('Error talking to server: %s' % e)
+                await self._connect()
+                return await proc()
+            except (
+                OSError,
+                HashConnectionError,
+                json.JSONDecodeError,
+                UnicodeDecodeError,
+            ) as e:
+                logger.warning("Error talking to server: %s" % e)
                 if count >= 3:
                     if not isinstance(e, HashConnectionError):
                         raise HashConnectionError(str(e))
                     raise e
-                self.close()
+                await self.close()
                 count += 1
 
-    def send_message(self, msg):
-        def get_line():
-            line = self.reader.readline()
+    async def send_message(self, msg):
+        async def get_line():
+            line = await self.reader.readline()
             if not line:
-                raise HashConnectionError('Connection closed')
+                raise HashConnectionError("Connection closed")
 
-            if not line.endswith('\n'):
-                raise HashConnectionError('Bad message %r' % message)
+            line = line.decode("utf-8")
+
+            if not line.endswith("\n"):
+                raise HashConnectionError("Bad message %r" % message)
 
             return line
 
-        def proc():
+        async def proc():
             for c in chunkify(json.dumps(msg), self.max_chunk):
-                self.writer.write(c)
-            self.writer.flush()
+                self.writer.write(c.encode("utf-8"))
+            await self.writer.drain()
 
-            l = get_line()
+            l = await get_line()
 
             m = json.loads(l)
-            if 'chunk-stream' in m:
+            if "chunk-stream" in m:
                 lines = []
                 while True:
-                    l = get_line().rstrip('\n')
+                    l = (await get_line()).rstrip("\n")
                     if not l:
                         break
                     lines.append(l)
 
-                m = json.loads(''.join(lines))
+                m = json.loads("".join(lines))
 
             return m
 
-        return self._send_wrapper(proc)
+        return await self._send_wrapper(proc)
 
-    def send_stream(self, msg):
-        def proc():
-            self.writer.write("%s\n" % msg)
-            self.writer.flush()
-            l = self.reader.readline()
+    async def send_stream(self, msg):
+        async def proc():
+            self.writer.write(("%s\n" % msg).encode("utf-8"))
+            await self.writer.drain()
+            l = await self.reader.readline()
             if not l:
-                raise HashConnectionError('Connection closed')
-            return l.rstrip()
+                raise HashConnectionError("Connection closed")
+            return l.decode("utf-8").rstrip()
 
-        return self._send_wrapper(proc)
+        return await self._send_wrapper(proc)
 
-    def _set_mode(self, new_mode):
+    async def _set_mode(self, new_mode):
         if new_mode == self.MODE_NORMAL and self.mode == self.MODE_GET_STREAM:
-            r = self.send_stream('END')
-            if r != 'ok':
-                raise HashConnectionError('Bad response from server %r' % r)
+            r = await self.send_stream("END")
+            if r != "ok":
+                raise HashConnectionError("Bad response from server %r" % r)
         elif new_mode == self.MODE_GET_STREAM and self.mode == self.MODE_NORMAL:
-            r = self.send_message({'get-stream': None})
-            if r != 'ok':
-                raise HashConnectionError('Bad response from server %r' % r)
+            r = await self.send_message({"get-stream": None})
+            if r != "ok":
+                raise HashConnectionError("Bad response from server %r" % r)
         elif new_mode != self.mode:
-            raise Exception('Undefined mode transition %r -> %r' % (self.mode, new_mode))
+            raise Exception(
+                "Undefined mode transition %r -> %r" % (self.mode, new_mode)
+            )
 
         self.mode = new_mode
 
-    def get_unihash(self, method, taskhash):
-        self._set_mode(self.MODE_GET_STREAM)
-        r = self.send_stream('%s %s' % (method, taskhash))
+    async def get_unihash(self, method, taskhash):
+        await self._set_mode(self.MODE_GET_STREAM)
+        r = await self.send_stream("%s %s" % (method, taskhash))
         if not r:
             return None
         return r
 
-    def report_unihash(self, taskhash, method, outhash, unihash, extra={}):
-        self._set_mode(self.MODE_NORMAL)
+    async def report_unihash(self, taskhash, method, outhash, unihash, extra={}):
+        await self._set_mode(self.MODE_NORMAL)
         m = extra.copy()
-        m['taskhash'] = taskhash
-        m['method'] = method
-        m['outhash'] = outhash
-        m['unihash'] = unihash
-        return self.send_message({'report': m})
+        m["taskhash"] = taskhash
+        m["method"] = method
+        m["outhash"] = outhash
+        m["unihash"] = unihash
+        return await self.send_message({"report": m})
 
-    def report_unihash_equiv(self, taskhash, method, unihash, extra={}):
-        self._set_mode(self.MODE_NORMAL)
+    async def report_unihash_equiv(self, taskhash, method, unihash, extra={}):
+        await self._set_mode(self.MODE_NORMAL)
         m = extra.copy()
-        m['taskhash'] = taskhash
-        m['method'] = method
-        m['unihash'] = unihash
-        return self.send_message({'report-equiv': m})
+        m["taskhash"] = taskhash
+        m["method"] = method
+        m["unihash"] = unihash
+        return await self.send_message({"report-equiv": m})
 
-    def get_taskhash(self, method, taskhash, all_properties=False):
-        self._set_mode(self.MODE_NORMAL)
-        return self.send_message({'get': {
-            'taskhash': taskhash,
-            'method': method,
-            'all': all_properties
-        }})
+    async def get_taskhash(self, method, taskhash, all_properties=False):
+        await self._set_mode(self.MODE_NORMAL)
+        return await self.send_message(
+            {"get": {"taskhash": taskhash, "method": method, "all": all_properties}}
+        )
 
-    def get_stats(self):
-        self._set_mode(self.MODE_NORMAL)
-        return self.send_message({'get-stats': None})
+    async def get_stats(self):
+        await self._set_mode(self.MODE_NORMAL)
+        return await self.send_message({"get-stats": None})
 
-    def reset_stats(self):
-        self._set_mode(self.MODE_NORMAL)
-        return self.send_message({'reset-stats': None})
+    async def reset_stats(self):
+        await self._set_mode(self.MODE_NORMAL)
+        return await self.send_message({"reset-stats": None})
+
+    async def backfill_wait(self):
+        await self._set_mode(self.MODE_NORMAL)
+        return (await self.send_message({"backfill-wait": None}))["tasks"]
+
+
+class Client(object):
+    def __init__(self):
+        self.client = AsyncClient()
+        self.loop = asyncio.new_event_loop()
+
+        for call in (
+            "connect_tcp",
+            "connect_unix",
+            "close",
+            "get_unihash",
+            "report_unihash",
+            "report_unihash_equiv",
+            "get_taskhash",
+            "get_stats",
+            "reset_stats",
+            "backfill_wait",
+        ):
+            downcall = getattr(self.client, call)
+            setattr(self, call, self._get_downcall_wrapper(downcall))
+
+    def _get_downcall_wrapper(self, downcall):
+        def wrapper(*args, **kwargs):
+            return self.loop.run_until_complete(downcall(*args, **kwargs))
+
+        return wrapper
+
+    @property
+    def max_chunk(self):
+        return self.client.max_chunk
+
+    @max_chunk.setter
+    def max_chunk(self, value):
+        self.client.max_chunk = value
diff --git a/poky/bitbake/lib/hashserv/server.py b/poky/bitbake/lib/hashserv/server.py
index 8105071..3ff4c51 100644
--- a/poky/bitbake/lib/hashserv/server.py
+++ b/poky/bitbake/lib/hashserv/server.py
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 #
 
-from contextlib import closing
+from contextlib import closing, contextmanager
 from datetime import datetime
 import asyncio
 import json
@@ -12,8 +12,9 @@
 import os
 import signal
 import socket
+import sys
 import time
-from . import chunkify, DEFAULT_MAX_CHUNK
+from . import chunkify, DEFAULT_MAX_CHUNK, create_async_client, TABLE_COLUMNS
 
 logger = logging.getLogger('hashserv.server')
 
@@ -111,16 +112,40 @@
 class ClientError(Exception):
     pass
 
+def insert_task(cursor, data, ignore=False):
+    keys = sorted(data.keys())
+    query = '''INSERT%s INTO tasks_v2 (%s) VALUES (%s)''' % (
+        " OR IGNORE" if ignore else "",
+        ', '.join(keys),
+        ', '.join(':' + k for k in keys))
+    cursor.execute(query, data)
+
+async def copy_from_upstream(client, db, method, taskhash):
+    d = await client.get_taskhash(method, taskhash, True)
+    if d is not None:
+        # Filter out unknown columns
+        d = {k: v for k, v in d.items() if k in TABLE_COLUMNS}
+        keys = sorted(d.keys())
+
+
+        with closing(db.cursor()) as cursor:
+            insert_task(cursor, d)
+            db.commit()
+
+    return d
+
 class ServerClient(object):
     FAST_QUERY = 'SELECT taskhash, method, unihash FROM tasks_v2 WHERE method=:method AND taskhash=:taskhash ORDER BY created ASC LIMIT 1'
     ALL_QUERY =  'SELECT *                         FROM tasks_v2 WHERE method=:method AND taskhash=:taskhash ORDER BY created ASC LIMIT 1'
 
-    def __init__(self, reader, writer, db, request_stats):
+    def __init__(self, reader, writer, db, request_stats, backfill_queue, upstream):
         self.reader = reader
         self.writer = writer
         self.db = db
         self.request_stats = request_stats
         self.max_chunk = DEFAULT_MAX_CHUNK
+        self.backfill_queue = backfill_queue
+        self.upstream = upstream
 
         self.handlers = {
             'get': self.handle_get,
@@ -130,10 +155,18 @@
             'get-stats': self.handle_get_stats,
             'reset-stats': self.handle_reset_stats,
             'chunk-stream': self.handle_chunk,
+            'backfill-wait': self.handle_backfill_wait,
         }
 
     async def process_requests(self):
+        if self.upstream is not None:
+            self.upstream_client = await create_async_client(self.upstream)
+        else:
+            self.upstream_client = None
+
         try:
+
+
             self.addr = self.writer.get_extra_info('peername')
             logger.debug('Client %r connected' % (self.addr,))
 
@@ -171,6 +204,9 @@
         except ClientError as e:
             logger.error(str(e))
         finally:
+            if self.upstream_client is not None:
+                await self.upstream_client.close()
+
             self.writer.close()
 
     async def dispatch_message(self, msg):
@@ -239,15 +275,19 @@
         if row is not None:
             logger.debug('Found equivalent task %s -> %s', (row['taskhash'], row['unihash']))
             d = {k: row[k] for k in row.keys()}
-
-            self.write_message(d)
+        elif self.upstream_client is not None:
+            d = await copy_from_upstream(self.upstream_client, self.db, method, taskhash)
         else:
-            self.write_message(None)
+            d = None
+
+        self.write_message(d)
 
     async def handle_get_stream(self, request):
         self.write_message('ok')
 
         while True:
+            upstream = None
+
             l = await self.reader.readline()
             if not l:
                 return
@@ -272,6 +312,12 @@
                 if row is not None:
                     msg = ('%s\n' % row['unihash']).encode('utf-8')
                     #logger.debug('Found equivalent task %s -> %s', (row['taskhash'], row['unihash']))
+                elif self.upstream_client is not None:
+                    upstream = await self.upstream_client.get_unihash(method, taskhash)
+                    if upstream:
+                        msg = ("%s\n" % upstream).encode("utf-8")
+                    else:
+                        msg = "\n".encode("utf-8")
                 else:
                     msg = '\n'.encode('utf-8')
 
@@ -282,6 +328,11 @@
 
             await self.writer.drain()
 
+            # Post to the backfill queue after writing the result to minimize
+            # the turn around time on a request
+            if upstream is not None:
+                await self.backfill_queue.put((method, taskhash))
+
     async def handle_report(self, data):
         with closing(self.db.cursor()) as cursor:
             cursor.execute('''
@@ -324,11 +375,7 @@
                     if k in data:
                         insert_data[k] = data[k]
 
-                cursor.execute('''INSERT INTO tasks_v2 (%s) VALUES (%s)''' % (
-                    ', '.join(sorted(insert_data.keys())),
-                    ', '.join(':' + k for k in sorted(insert_data.keys()))),
-                    insert_data)
-
+                insert_task(cursor, insert_data)
                 self.db.commit()
 
                 logger.info('Adding taskhash %s with unihash %s',
@@ -358,11 +405,7 @@
                 if k in data:
                     insert_data[k] = data[k]
 
-            cursor.execute('''INSERT OR IGNORE INTO tasks_v2 (%s) VALUES (%s)''' % (
-                ', '.join(sorted(insert_data.keys())),
-                ', '.join(':' + k for k in sorted(insert_data.keys()))),
-                insert_data)
-
+            insert_task(cursor, insert_data, ignore=True)
             self.db.commit()
 
             # Fetch the unihash that will be reported for the taskhash. If the
@@ -394,6 +437,13 @@
         self.request_stats.reset()
         self.write_message(d)
 
+    async def handle_backfill_wait(self, request):
+        d = {
+            'tasks': self.backfill_queue.qsize(),
+        }
+        await self.backfill_queue.join()
+        self.write_message(d)
+
     def query_equivalent(self, method, taskhash, query):
         # This is part of the inner loop and must be as fast as possible
         try:
@@ -405,7 +455,7 @@
 
 
 class Server(object):
-    def __init__(self, db, loop=None):
+    def __init__(self, db, loop=None, upstream=None):
         self.request_stats = Stats()
         self.db = db
 
@@ -416,6 +466,8 @@
             self.loop = loop
             self.close_loop = False
 
+        self.upstream = upstream
+
         self._cleanup_socket = None
 
     def start_tcp_server(self, host, port):
@@ -458,7 +510,7 @@
     async def handle_client(self, reader, writer):
         # writer.transport.set_write_buffer_limits(0)
         try:
-            client = ServerClient(reader, writer, self.db, self.request_stats)
+            client = ServerClient(reader, writer, self.db, self.request_stats, self.backfill_queue, self.upstream)
             await client.process_requests()
         except Exception as e:
             import traceback
@@ -467,23 +519,60 @@
             writer.close()
         logger.info('Client disconnected')
 
+    @contextmanager
+    def _backfill_worker(self):
+        async def backfill_worker_task():
+            client = await create_async_client(self.upstream)
+            try:
+                while True:
+                    item = await self.backfill_queue.get()
+                    if item is None:
+                        self.backfill_queue.task_done()
+                        break
+                    method, taskhash = item
+                    await copy_from_upstream(client, self.db, method, taskhash)
+                    self.backfill_queue.task_done()
+            finally:
+                await client.close()
+
+        async def join_worker(worker):
+            await self.backfill_queue.put(None)
+            await worker
+
+        if self.upstream is not None:
+            worker = asyncio.ensure_future(backfill_worker_task())
+            try:
+                yield
+            finally:
+                self.loop.run_until_complete(join_worker(worker))
+        else:
+            yield
+
     def serve_forever(self):
         def signal_handler():
             self.loop.stop()
 
-        self.loop.add_signal_handler(signal.SIGTERM, signal_handler)
-
+        asyncio.set_event_loop(self.loop)
         try:
-            self.loop.run_forever()
-        except KeyboardInterrupt:
-            pass
+            self.backfill_queue = asyncio.Queue()
 
-        self.server.close()
-        self.loop.run_until_complete(self.server.wait_closed())
-        logger.info('Server shutting down')
+            self.loop.add_signal_handler(signal.SIGTERM, signal_handler)
 
-        if self.close_loop:
-            self.loop.close()
+            with self._backfill_worker():
+                try:
+                    self.loop.run_forever()
+                except KeyboardInterrupt:
+                    pass
 
-        if self._cleanup_socket is not None:
-            self._cleanup_socket()
+                self.server.close()
+
+            self.loop.run_until_complete(self.server.wait_closed())
+            logger.info('Server shutting down')
+        finally:
+            if self.close_loop:
+                if sys.version_info >= (3, 6):
+                    self.loop.run_until_complete(self.loop.shutdown_asyncgens())
+                self.loop.close()
+
+            if self._cleanup_socket is not None:
+                self._cleanup_socket()
diff --git a/poky/bitbake/lib/hashserv/tests.py b/poky/bitbake/lib/hashserv/tests.py
index 4566f24..3dd9a31 100644
--- a/poky/bitbake/lib/hashserv/tests.py
+++ b/poky/bitbake/lib/hashserv/tests.py
@@ -16,35 +16,54 @@
 import unittest
 import socket
 
+def _run_server(server, idx):
+    # logging.basicConfig(level=logging.DEBUG, filename='bbhashserv.log', filemode='w',
+    #                     format='%(levelname)s %(filename)s:%(lineno)d %(message)s')
+    sys.stdout = open('bbhashserv-%d.log' % idx, 'w')
+    sys.stderr = sys.stdout
+    server.serve_forever()
 
 class TestHashEquivalenceServer(object):
     METHOD = 'TestMethod'
 
-    def _run_server(self):
-        # logging.basicConfig(level=logging.DEBUG, filename='bbhashserv.log', filemode='w',
-        #                     format='%(levelname)s %(filename)s:%(lineno)d %(message)s')
-        self.server.serve_forever()
+    server_index = 0
+
+    def start_server(self, dbpath=None, upstream=None):
+        self.server_index += 1
+        if dbpath is None:
+            dbpath = os.path.join(self.temp_dir.name, "db%d.sqlite" % self.server_index)
+
+        def cleanup_thread(thread):
+            thread.terminate()
+            thread.join()
+
+        server = create_server(self.get_server_addr(self.server_index), dbpath, upstream=upstream)
+        server.dbpath = dbpath
+
+        server.thread = multiprocessing.Process(target=_run_server, args=(server, self.server_index))
+        server.thread.start()
+        self.addCleanup(cleanup_thread, server.thread)
+
+        def cleanup_client(client):
+            client.close()
+
+        client = create_client(server.address)
+        self.addCleanup(cleanup_client, client)
+
+        return (client, server)
 
     def setUp(self):
         if sys.version_info < (3, 5, 0):
             self.skipTest('Python 3.5 or later required')
 
         self.temp_dir = tempfile.TemporaryDirectory(prefix='bb-hashserv')
-        self.dbfile = os.path.join(self.temp_dir.name, 'db.sqlite')
+        self.addCleanup(self.temp_dir.cleanup)
 
-        self.server = create_server(self.get_server_addr(), self.dbfile)
-        self.server_thread = multiprocessing.Process(target=self._run_server)
-        self.server_thread.start()
-        self.client = create_client(self.server.address)
+        (self.client, self.server) = self.start_server()
 
-    def tearDown(self):
-        # Shutdown server
-        s = getattr(self, 'server', None)
-        if s is not None:
-            self.server_thread.terminate()
-            self.server_thread.join()
-        self.client.close()
-        self.temp_dir.cleanup()
+    def assertClientGetHash(self, client, taskhash, unihash):
+        result = client.get_unihash(self.METHOD, taskhash)
+        self.assertEqual(result, unihash)
 
     def test_create_hash(self):
         # Simple test that hashes can be created
@@ -52,8 +71,7 @@
         outhash = '2765d4a5884be49b28601445c2760c5f21e7e5c0ee2b7e3fce98fd7e5970796f'
         unihash = 'f46d3fbb439bd9b921095da657a4de906510d2cd'
 
-        result = self.client.get_unihash(self.METHOD, taskhash)
-        self.assertIsNone(result, msg='Found unexpected task, %r' % result)
+        self.assertClientGetHash(self.client, taskhash, None)
 
         result = self.client.report_unihash(taskhash, self.METHOD, outhash, unihash)
         self.assertEqual(result['unihash'], unihash, 'Server returned bad unihash')
@@ -84,22 +102,19 @@
         unihash = '218e57509998197d570e2c98512d0105985dffc9'
         self.client.report_unihash(taskhash, self.METHOD, outhash, unihash)
 
-        result = self.client.get_unihash(self.METHOD, taskhash)
-        self.assertEqual(result, unihash)
+        self.assertClientGetHash(self.client, taskhash, unihash)
 
         outhash2 = '0904a7fe3dc712d9fd8a74a616ddca2a825a8ee97adf0bd3fc86082c7639914d'
         unihash2 = 'ae9a7d252735f0dafcdb10e2e02561ca3a47314c'
         self.client.report_unihash(taskhash, self.METHOD, outhash2, unihash2)
 
-        result = self.client.get_unihash(self.METHOD, taskhash)
-        self.assertEqual(result, unihash)
+        self.assertClientGetHash(self.client, taskhash, unihash)
 
         outhash3 = '77623a549b5b1a31e3732dfa8fe61d7ce5d44b3370f253c5360e136b852967b4'
         unihash3 = '9217a7d6398518e5dc002ed58f2cbbbc78696603'
         self.client.report_unihash(taskhash, self.METHOD, outhash3, unihash3)
 
-        result = self.client.get_unihash(self.METHOD, taskhash)
-        self.assertEqual(result, unihash)
+        self.assertClientGetHash(self.client, taskhash, unihash)
 
     def test_huge_message(self):
         # Simple test that hashes can be created
@@ -107,8 +122,7 @@
         outhash = '3c979c3db45c569f51ab7626a4651074be3a9d11a84b1db076f5b14f7d39db44'
         unihash = '90e9bc1d1f094c51824adca7f8ea79a048d68824'
 
-        result = self.client.get_unihash(self.METHOD, taskhash)
-        self.assertIsNone(result, msg='Found unexpected task, %r' % result)
+        self.assertClientGetHash(self.client, taskhash, None)
 
         siginfo = "0" * (self.client.max_chunk * 4)
 
@@ -156,14 +170,83 @@
 
         self.assertFalse(failures)
 
+    def test_upstream_server(self):
+        # Tests upstream server support. This is done by creating two servers
+        # that share a database file. The downstream server has it upstream
+        # set to the test server, whereas the side server doesn't. This allows
+        # verification that the hash requests are being proxied to the upstream
+        # server by verifying that they appear on the downstream client, but not
+        # the side client. It also verifies that the results are pulled into
+        # the downstream database by checking that the downstream and side servers
+        # match after the downstream is done waiting for all backfill tasks
+        (down_client, down_server) = self.start_server(upstream=self.server.address)
+        (side_client, side_server) = self.start_server(dbpath=down_server.dbpath)
+
+        def check_hash(taskhash, unihash, old_sidehash):
+            nonlocal down_client
+            nonlocal side_client
+
+            # check upstream server
+            self.assertClientGetHash(self.client, taskhash, unihash)
+
+            # Hash should *not* be present on the side server
+            self.assertClientGetHash(side_client, taskhash, old_sidehash)
+
+            # Hash should be present on the downstream server, since it
+            # will defer to the upstream server. This will trigger
+            # the backfill in the downstream server
+            self.assertClientGetHash(down_client, taskhash, unihash)
+
+            # After waiting for the downstream client to finish backfilling the
+            # task from the upstream server, it should appear in the side server
+            # since the database is populated
+            down_client.backfill_wait()
+            self.assertClientGetHash(side_client, taskhash, unihash)
+
+        # Basic report
+        taskhash = '8aa96fcffb5831b3c2c0cb75f0431e3f8b20554a'
+        outhash = 'afe240a439959ce86f5e322f8c208e1fedefea9e813f2140c81af866cc9edf7e'
+        unihash = '218e57509998197d570e2c98512d0105985dffc9'
+        self.client.report_unihash(taskhash, self.METHOD, outhash, unihash)
+
+        check_hash(taskhash, unihash, None)
+
+        # Duplicated taskhash with multiple output hashes and unihashes.
+        # All servers should agree with the originally reported hash
+        outhash2 = '0904a7fe3dc712d9fd8a74a616ddca2a825a8ee97adf0bd3fc86082c7639914d'
+        unihash2 = 'ae9a7d252735f0dafcdb10e2e02561ca3a47314c'
+        self.client.report_unihash(taskhash, self.METHOD, outhash2, unihash2)
+
+        check_hash(taskhash, unihash, unihash)
+
+        # Report an equivalent task. The sideload will originally report
+        # no unihash until backfilled
+        taskhash3 = "044c2ec8aaf480685a00ff6ff49e6162e6ad34e1"
+        unihash3 = "def64766090d28f627e816454ed46894bb3aab36"
+        self.client.report_unihash(taskhash3, self.METHOD, outhash, unihash3)
+
+        check_hash(taskhash3, unihash, None)
+
+        # Test that reporting a unihash in the downstream client isn't
+        # propagating to the upstream server
+        taskhash4 = "e3da00593d6a7fb435c7e2114976c59c5fd6d561"
+        outhash4 = "1cf8713e645f491eb9c959d20b5cae1c47133a292626dda9b10709857cbe688a"
+        unihash4 = "3b5d3d83f07f259e9086fcb422c855286e18a57d"
+        down_client.report_unihash(taskhash4, self.METHOD, outhash4, unihash4)
+        down_client.backfill_wait()
+
+        self.assertClientGetHash(down_client, taskhash4, unihash4)
+        self.assertClientGetHash(side_client, taskhash4, unihash4)
+        self.assertClientGetHash(self.client, taskhash4, None)
+
 
 class TestHashEquivalenceUnixServer(TestHashEquivalenceServer, unittest.TestCase):
-    def get_server_addr(self):
-        return "unix://" + os.path.join(self.temp_dir.name, 'sock')
+    def get_server_addr(self, server_idx):
+        return "unix://" + os.path.join(self.temp_dir.name, 'sock%d' % server_idx)
 
 
 class TestHashEquivalenceTCPServer(TestHashEquivalenceServer, unittest.TestCase):
-    def get_server_addr(self):
+    def get_server_addr(self, server_idx):
         # Some hosts cause asyncio module to misbehave, when IPv6 is not enabled.
         # If IPv6 is enabled, it should be safe to use localhost directly, in general
         # case it is more reliable to resolve the IP address explicitly.