diff --git a/poky/bitbake/bin/bitbake-getvar b/poky/bitbake/bin/bitbake-getvar
index 4a9eb4f..8901f99 100755
--- a/poky/bitbake/bin/bitbake-getvar
+++ b/poky/bitbake/bin/bitbake-getvar
@@ -26,26 +26,35 @@
     parser.add_argument('-f', '--flag', help='Specify a variable flag to query (with --value)', default=None)
     parser.add_argument('--value', help='Only report the value, no history and no variable name', action="store_true")
     parser.add_argument('-q', '--quiet', help='Silence bitbake server logging', action="store_true")
+    parser.add_argument('--ignore-undefined', help='Suppress any errors related to undefined variables', action="store_true")
     args = parser.parse_args()
 
-    if args.unexpand and not args.value:
-        print("--unexpand only makes sense with --value")
-        sys.exit(1)
+    if not args.value:
+        if args.unexpand:
+            sys.exit("--unexpand only makes sense with --value")
 
-    if args.flag and not args.value:
-        print("--flag only makes sense with --value")
-        sys.exit(1)
+        if args.flag:
+            sys.exit("--flag only makes sense with --value")
 
-    with bb.tinfoil.Tinfoil(tracking=True, setup_logging=not args.quiet) as tinfoil:
+    quiet = args.quiet or args.value
+    with bb.tinfoil.Tinfoil(tracking=True, setup_logging=not quiet) as tinfoil:
         if args.recipe:
-            tinfoil.prepare(quiet=2)
+            tinfoil.prepare(quiet=3 if quiet else 2)
             d = tinfoil.parse_recipe(args.recipe)
         else:
             tinfoil.prepare(quiet=2, config_only=True)
             d = tinfoil.config_data
+
+        value = None
         if args.flag:
-            print(str(d.getVarFlag(args.variable, args.flag, expand=(not args.unexpand))))
-        elif args.value:
-            print(str(d.getVar(args.variable, expand=(not args.unexpand))))
+            value = d.getVarFlag(args.variable, args.flag, expand=not args.unexpand)
+            if value is None and not args.ignore_undefined:
+                sys.exit(f"The flag '{args.flag}' is not defined for variable '{args.variable}'")
+        else:
+            value = d.getVar(args.variable, expand=not args.unexpand)
+            if value is None and not args.ignore_undefined:
+                sys.exit(f"The variable '{args.variable}' is not defined")
+        if args.value:
+            print(str(value if value is not None else ""))
         else:
             bb.data.emit_var(args.variable, d=d, all=True)
diff --git a/poky/bitbake/bin/bitbake-worker b/poky/bitbake/bin/bitbake-worker
index 451e692..609e276 100755
--- a/poky/bitbake/bin/bitbake-worker
+++ b/poky/bitbake/bin/bitbake-worker
@@ -91,19 +91,19 @@
 worker_thread_exit = False
 
 def worker_flush(worker_queue):
-    worker_queue_int = b""
+    worker_queue_int = bytearray()
     global worker_pipe, worker_thread_exit
 
     while True:
         try:
-            worker_queue_int = worker_queue_int + worker_queue.get(True, 1)
+            worker_queue_int.extend(worker_queue.get(True, 1))
         except queue.Empty:
             pass
         while (worker_queue_int or not worker_queue.empty()):
             try:
                 (_, ready, _) = select.select([], [worker_pipe], [], 1)
                 if not worker_queue.empty():
-                    worker_queue_int = worker_queue_int + worker_queue.get()
+                    worker_queue_int.extend(worker_queue.get())
                 written = os.write(worker_pipe, worker_queue_int)
                 worker_queue_int = worker_queue_int[written:]
             except (IOError, OSError) as e:
@@ -346,12 +346,12 @@
         if pipeout:
             pipeout.close()
         bb.utils.nonblockingfd(self.input)
-        self.queue = b""
+        self.queue = bytearray()
 
     def read(self):
         start = len(self.queue)
         try:
-            self.queue = self.queue + (self.input.read(102400) or b"")
+            self.queue.extend(self.input.read(102400) or b"")
         except (OSError, IOError) as e:
             if e.errno != errno.EAGAIN:
                 raise
@@ -379,7 +379,7 @@
     def __init__(self, din):
         self.input = din
         bb.utils.nonblockingfd(self.input)
-        self.queue = b""
+        self.queue = bytearray()
         self.cookercfg = None
         self.databuilder = None
         self.data = None
@@ -413,7 +413,7 @@
                     if len(r) == 0:
                         # EOF on pipe, server must have terminated
                         self.sigterm_exception(signal.SIGTERM, None)
-                    self.queue = self.queue + r
+                    self.queue.extend(r)
                 except (OSError, IOError):
                     pass
             if len(self.queue):