diff --git a/bitbake/lib/bb/build.py b/bitbake/lib/bb/build.py
new file mode 100644
index 0000000..948c395
--- /dev/null
+++ b/bitbake/lib/bb/build.py
@@ -0,0 +1,770 @@
+# ex:ts=4:sw=4:sts=4:et
+# -*- tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#
+# BitBake 'Build' implementation
+#
+# Core code for function execution and task handling in the
+# BitBake build tools.
+#
+# Copyright (C) 2003, 2004  Chris Larson
+#
+# Based on Gentoo's portage.py.
+#
+# 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.
+#
+# Based on functions from the base bb module, Copyright 2003 Holger Schurig
+
+import os
+import sys
+import logging
+import shlex
+import glob
+import time
+import stat
+import bb
+import bb.msg
+import bb.process
+from contextlib import nested
+from bb import event, utils
+
+bblogger = logging.getLogger('BitBake')
+logger = logging.getLogger('BitBake.Build')
+
+NULL = open(os.devnull, 'r+')
+
+__mtime_cache = {}
+
+def cached_mtime_noerror(f):
+    if f not in __mtime_cache:
+        try:
+            __mtime_cache[f] = os.stat(f)[stat.ST_MTIME]
+        except OSError:
+            return 0
+    return __mtime_cache[f]
+
+def reset_cache():
+    global __mtime_cache
+    __mtime_cache = {}
+
+# When we execute a Python function, we'd like certain things
+# in all namespaces, hence we add them to __builtins__.
+# If we do not do this and use the exec globals, they will
+# not be available to subfunctions.
+__builtins__['bb'] = bb
+__builtins__['os'] = os
+
+class FuncFailed(Exception):
+    def __init__(self, name = None, logfile = None):
+        self.logfile = logfile
+        self.name = name
+        if name:
+            self.msg = 'Function failed: %s' % name
+        else:
+            self.msg = "Function failed"
+
+    def __str__(self):
+        if self.logfile and os.path.exists(self.logfile):
+            msg = ("%s (log file is located at %s)" %
+                   (self.msg, self.logfile))
+        else:
+            msg = self.msg
+        return msg
+
+class TaskBase(event.Event):
+    """Base class for task events"""
+
+    def __init__(self, t, logfile, d):
+        self._task = t
+        self._package = d.getVar("PF", True)
+        self.taskfile = d.getVar("FILE", True)
+        self.taskname = self._task
+        self.logfile = logfile
+        self.time = time.time()
+        event.Event.__init__(self)
+        self._message = "recipe %s: task %s: %s" % (d.getVar("PF", True), t, self.getDisplayName())
+
+    def getTask(self):
+        return self._task
+
+    def setTask(self, task):
+        self._task = task
+
+    def getDisplayName(self):
+        return bb.event.getName(self)[4:]
+
+    task = property(getTask, setTask, None, "task property")
+
+class TaskStarted(TaskBase):
+    """Task execution started"""
+    def __init__(self, t, logfile, taskflags, d):
+        super(TaskStarted, self).__init__(t, logfile, d)
+        self.taskflags = taskflags
+
+class TaskSucceeded(TaskBase):
+    """Task execution completed"""
+
+class TaskFailed(TaskBase):
+    """Task execution failed"""
+
+    def __init__(self, task, logfile, metadata, errprinted = False):
+        self.errprinted = errprinted
+        super(TaskFailed, self).__init__(task, logfile, metadata)
+
+class TaskFailedSilent(TaskBase):
+    """Task execution failed (silently)"""
+    def getDisplayName(self):
+        # Don't need to tell the user it was silent
+        return "Failed"
+
+class TaskInvalid(TaskBase):
+
+    def __init__(self, task, metadata):
+        super(TaskInvalid, self).__init__(task, None, metadata)
+        self._message = "No such task '%s'" % task
+
+
+class LogTee(object):
+    def __init__(self, logger, outfile):
+        self.outfile = outfile
+        self.logger = logger
+        self.name = self.outfile.name
+
+    def write(self, string):
+        self.logger.plain(string)
+        self.outfile.write(string)
+
+    def __enter__(self):
+        self.outfile.__enter__()
+        return self
+
+    def __exit__(self, *excinfo):
+        self.outfile.__exit__(*excinfo)
+
+    def __repr__(self):
+        return '<LogTee {0}>'.format(self.name)
+    def flush(self):
+        self.outfile.flush()
+
+def exec_func(func, d, dirs = None):
+    """Execute a BB 'function'"""
+
+    body = d.getVar(func, False)
+    if not body:
+        if body is None:
+            logger.warn("Function %s doesn't exist", func)
+        return
+
+    flags = d.getVarFlags(func)
+    cleandirs = flags.get('cleandirs')
+    if cleandirs:
+        for cdir in d.expand(cleandirs).split():
+            bb.utils.remove(cdir, True)
+            bb.utils.mkdirhier(cdir)
+
+    if dirs is None:
+        dirs = flags.get('dirs')
+        if dirs:
+            dirs = d.expand(dirs).split()
+
+    if dirs:
+        for adir in dirs:
+            bb.utils.mkdirhier(adir)
+        adir = dirs[-1]
+    else:
+        adir = d.getVar('B', True)
+        bb.utils.mkdirhier(adir)
+
+    ispython = flags.get('python')
+
+    lockflag = flags.get('lockfiles')
+    if lockflag:
+        lockfiles = [f for f in d.expand(lockflag).split()]
+    else:
+        lockfiles = None
+
+    tempdir = d.getVar('T', True)
+
+    # or func allows items to be executed outside of the normal
+    # task set, such as buildhistory
+    task = d.getVar('BB_RUNTASK', True) or func
+    if task == func:
+        taskfunc = task
+    else:
+        taskfunc = "%s.%s" % (task, func)
+
+    runfmt = d.getVar('BB_RUNFMT', True) or "run.{func}.{pid}"
+    runfn = runfmt.format(taskfunc=taskfunc, task=task, func=func, pid=os.getpid())
+    runfile = os.path.join(tempdir, runfn)
+    bb.utils.mkdirhier(os.path.dirname(runfile))
+
+    # Setup the courtesy link to the runfn, only for tasks
+    # we create the link 'just' before the run script is created
+    # if we create it after, and if the run script fails, then the
+    # link won't be created as an exception would be fired.
+    if task == func:
+        runlink = os.path.join(tempdir, 'run.{0}'.format(task))
+        if runlink:
+            bb.utils.remove(runlink)
+
+            try:
+                os.symlink(runfn, runlink)
+            except OSError:
+                pass
+
+    with bb.utils.fileslocked(lockfiles):
+        if ispython:
+            exec_func_python(func, d, runfile, cwd=adir)
+        else:
+            exec_func_shell(func, d, runfile, cwd=adir)
+
+_functionfmt = """
+def {function}(d):
+{body}
+
+{function}(d)
+"""
+logformatter = bb.msg.BBLogFormatter("%(levelname)s: %(message)s")
+def exec_func_python(func, d, runfile, cwd=None):
+    """Execute a python BB 'function'"""
+
+    bbfile = d.getVar('FILE', True)
+    code = _functionfmt.format(function=func, body=d.getVar(func, True))
+    bb.utils.mkdirhier(os.path.dirname(runfile))
+    with open(runfile, 'w') as script:
+        bb.data.emit_func_python(func, script, d)
+
+    if cwd:
+        try:
+            olddir = os.getcwd()
+        except OSError:
+            olddir = None
+        os.chdir(cwd)
+
+    bb.debug(2, "Executing python function %s" % func)
+
+    try:
+        comp = utils.better_compile(code, func, bbfile)
+        utils.better_exec(comp, {"d": d}, code, bbfile)
+    except (bb.parse.SkipRecipe, bb.build.FuncFailed):
+        raise
+    except:
+        raise FuncFailed(func, None)
+    finally:
+        bb.debug(2, "Python function %s finished" % func)
+
+        if cwd and olddir:
+            try:
+                os.chdir(olddir)
+            except OSError:
+                pass
+
+def shell_trap_code():
+    return '''#!/bin/sh\n
+# Emit a useful diagnostic if something fails:
+bb_exit_handler() {
+    ret=$?
+    case $ret in
+    0)  ;;
+    *)  case $BASH_VERSION in
+        "")   echo "WARNING: exit code $ret from a shell command.";;
+        *)    echo "WARNING: ${BASH_SOURCE[0]}:${BASH_LINENO[0]} exit $ret from
+  \"$BASH_COMMAND\"";;
+        esac
+        exit $ret
+    esac
+}
+trap 'bb_exit_handler' 0
+set -e
+'''
+
+def exec_func_shell(func, d, runfile, cwd=None):
+    """Execute a shell function from the metadata
+
+    Note on directory behavior.  The 'dirs' varflag should contain a list
+    of the directories you need created prior to execution.  The last
+    item in the list is where we will chdir/cd to.
+    """
+
+    # Don't let the emitted shell script override PWD
+    d.delVarFlag('PWD', 'export')
+
+    with open(runfile, 'w') as script:
+        script.write(shell_trap_code())
+
+        bb.data.emit_func(func, script, d)
+
+        if bb.msg.loggerVerboseLogs:
+            script.write("set -x\n")
+        if cwd:
+            script.write("cd '%s'\n" % cwd)
+        script.write("%s\n" % func)
+        script.write('''
+# cleanup
+ret=$?
+trap '' 0
+exit $ret
+''')
+
+    os.chmod(runfile, 0775)
+
+    cmd = runfile
+    if d.getVarFlag(func, 'fakeroot'):
+        fakerootcmd = d.getVar('FAKEROOT', True)
+        if fakerootcmd:
+            cmd = [fakerootcmd, runfile]
+
+    if bb.msg.loggerDefaultVerbose:
+        logfile = LogTee(logger, sys.stdout)
+    else:
+        logfile = sys.stdout
+
+    def readfifo(data):
+        lines = data.split('\0')
+        for line in lines:
+            splitval = line.split(' ', 1)
+            cmd = splitval[0]
+            if len(splitval) > 1:
+                value = splitval[1]
+            else:
+                value = ''
+            if cmd == 'bbplain':
+                bb.plain(value)
+            elif cmd == 'bbnote':
+                bb.note(value)
+            elif cmd == 'bbwarn':
+                bb.warn(value)
+            elif cmd == 'bberror':
+                bb.error(value)
+            elif cmd == 'bbfatal':
+                # The caller will call exit themselves, so bb.error() is
+                # what we want here rather than bb.fatal()
+                bb.error(value)
+            elif cmd == 'bbfatal_log':
+                bb.error(value, forcelog=True)
+            elif cmd == 'bbdebug':
+                splitval = value.split(' ', 1)
+                level = int(splitval[0])
+                value = splitval[1]
+                bb.debug(level, value)
+
+    tempdir = d.getVar('T', True)
+    fifopath = os.path.join(tempdir, 'fifo.%s' % os.getpid())
+    if os.path.exists(fifopath):
+        os.unlink(fifopath)
+    os.mkfifo(fifopath)
+    with open(fifopath, 'r+') as fifo:
+        try:
+            bb.debug(2, "Executing shell function %s" % func)
+
+            try:
+                with open(os.devnull, 'r+') as stdin:
+                    bb.process.run(cmd, shell=False, stdin=stdin, log=logfile, extrafiles=[(fifo,readfifo)])
+            except bb.process.CmdError:
+                logfn = d.getVar('BB_LOGFILE', True)
+                raise FuncFailed(func, logfn)
+        finally:
+            os.unlink(fifopath)
+
+    bb.debug(2, "Shell function %s finished" % func)
+
+def _task_data(fn, task, d):
+    localdata = bb.data.createCopy(d)
+    localdata.setVar('BB_FILENAME', fn)
+    localdata.setVar('BB_CURRENTTASK', task[3:])
+    localdata.setVar('OVERRIDES', 'task-%s:%s' %
+                     (task[3:].replace('_', '-'), d.getVar('OVERRIDES', False)))
+    localdata.finalize()
+    bb.data.expandKeys(localdata)
+    return localdata
+
+def _exec_task(fn, task, d, quieterr):
+    """Execute a BB 'task'
+
+    Execution of a task involves a bit more setup than executing a function,
+    running it with its own local metadata, and with some useful variables set.
+    """
+    if not d.getVarFlag(task, 'task'):
+        event.fire(TaskInvalid(task, d), d)
+        logger.error("No such task: %s" % task)
+        return 1
+
+    logger.debug(1, "Executing task %s", task)
+
+    localdata = _task_data(fn, task, d)
+    tempdir = localdata.getVar('T', True)
+    if not tempdir:
+        bb.fatal("T variable not set, unable to build")
+
+    # Change nice level if we're asked to
+    nice = localdata.getVar("BB_TASK_NICE_LEVEL", True)
+    if nice:
+        curnice = os.nice(0)
+        nice = int(nice) - curnice
+        newnice = os.nice(nice)
+        logger.debug(1, "Renice to %s " % newnice)
+
+    bb.utils.mkdirhier(tempdir)
+
+    # Determine the logfile to generate
+    logfmt = localdata.getVar('BB_LOGFMT', True) or 'log.{task}.{pid}'
+    logbase = logfmt.format(task=task, pid=os.getpid())
+
+    # Document the order of the tasks...
+    logorder = os.path.join(tempdir, 'log.task_order')
+    try:
+        with open(logorder, 'a') as logorderfile:
+            logorderfile.write('{0} ({1}): {2}\n'.format(task, os.getpid(), logbase))
+    except OSError:
+        logger.exception("Opening log file '%s'", logorder)
+        pass
+
+    # Setup the courtesy link to the logfn
+    loglink = os.path.join(tempdir, 'log.{0}'.format(task))
+    logfn = os.path.join(tempdir, logbase)
+    if loglink:
+        bb.utils.remove(loglink)
+
+        try:
+           os.symlink(logbase, loglink)
+        except OSError:
+           pass
+
+    prefuncs = localdata.getVarFlag(task, 'prefuncs', expand=True)
+    postfuncs = localdata.getVarFlag(task, 'postfuncs', expand=True)
+
+    class ErrorCheckHandler(logging.Handler):
+        def __init__(self):
+            self.triggered = False
+            logging.Handler.__init__(self, logging.ERROR)
+        def emit(self, record):
+            if getattr(record, 'forcelog', False):
+                self.triggered = False
+            else:
+                self.triggered = True
+
+    # Handle logfiles
+    si = open('/dev/null', 'r')
+    try:
+        bb.utils.mkdirhier(os.path.dirname(logfn))
+        logfile = open(logfn, 'w')
+    except OSError:
+        logger.exception("Opening log file '%s'", logfn)
+        pass
+
+    # Dup the existing fds so we dont lose them
+    osi = [os.dup(sys.stdin.fileno()), sys.stdin.fileno()]
+    oso = [os.dup(sys.stdout.fileno()), sys.stdout.fileno()]
+    ose = [os.dup(sys.stderr.fileno()), sys.stderr.fileno()]
+
+    # Replace those fds with our own
+    os.dup2(si.fileno(), osi[1])
+    os.dup2(logfile.fileno(), oso[1])
+    os.dup2(logfile.fileno(), ose[1])
+
+    # Ensure Python logging goes to the logfile
+    handler = logging.StreamHandler(logfile)
+    handler.setFormatter(logformatter)
+    # Always enable full debug output into task logfiles
+    handler.setLevel(logging.DEBUG - 2)
+    bblogger.addHandler(handler)
+
+    errchk = ErrorCheckHandler()
+    bblogger.addHandler(errchk)
+
+    localdata.setVar('BB_LOGFILE', logfn)
+    localdata.setVar('BB_RUNTASK', task)
+
+    flags = localdata.getVarFlags(task)
+
+    event.fire(TaskStarted(task, logfn, flags, localdata), localdata)
+    try:
+        for func in (prefuncs or '').split():
+            exec_func(func, localdata)
+        exec_func(task, localdata)
+        for func in (postfuncs or '').split():
+            exec_func(func, localdata)
+    except FuncFailed as exc:
+        if quieterr:
+            event.fire(TaskFailedSilent(task, logfn, localdata), localdata)
+        else:
+            errprinted = errchk.triggered
+            logger.error(str(exc))
+            event.fire(TaskFailed(task, logfn, localdata, errprinted), localdata)
+        return 1
+    finally:
+        sys.stdout.flush()
+        sys.stderr.flush()
+
+        bblogger.removeHandler(handler)
+
+        # Restore the backup fds
+        os.dup2(osi[0], osi[1])
+        os.dup2(oso[0], oso[1])
+        os.dup2(ose[0], ose[1])
+
+        # Close the backup fds
+        os.close(osi[0])
+        os.close(oso[0])
+        os.close(ose[0])
+        si.close()
+
+        logfile.close()
+        if os.path.exists(logfn) and os.path.getsize(logfn) == 0:
+            logger.debug(2, "Zero size logfn %s, removing", logfn)
+            bb.utils.remove(logfn)
+            bb.utils.remove(loglink)
+    event.fire(TaskSucceeded(task, logfn, localdata), localdata)
+
+    if not localdata.getVarFlag(task, 'nostamp') and not localdata.getVarFlag(task, 'selfstamp'):
+        make_stamp(task, localdata)
+
+    return 0
+
+def exec_task(fn, task, d, profile = False):
+    try:
+        quieterr = False
+        if d.getVarFlag(task, "quieterrors") is not None:
+            quieterr = True
+
+        if profile:
+            profname = "profile-%s.log" % (d.getVar("PN", True) + "-" + task)
+            try:
+                import cProfile as profile
+            except:
+                import profile
+            prof = profile.Profile()
+            ret = profile.Profile.runcall(prof, _exec_task, fn, task, d, quieterr)
+            prof.dump_stats(profname)
+            bb.utils.process_profilelog(profname)
+
+            return ret
+        else:
+            return _exec_task(fn, task, d, quieterr)
+
+    except Exception:
+        from traceback import format_exc
+        if not quieterr:
+            logger.error("Build of %s failed" % (task))
+            logger.error(format_exc())
+            failedevent = TaskFailed(task, None, d, True)
+            event.fire(failedevent, d)
+        return 1
+
+def stamp_internal(taskname, d, file_name, baseonly=False):
+    """
+    Internal stamp helper function
+    Makes sure the stamp directory exists
+    Returns the stamp path+filename
+
+    In the bitbake core, d can be a CacheData and file_name will be set.
+    When called in task context, d will be a data store, file_name will not be set
+    """
+    taskflagname = taskname
+    if taskname.endswith("_setscene") and taskname != "do_setscene":
+        taskflagname = taskname.replace("_setscene", "")
+
+    if file_name:
+        stamp = d.stamp_base[file_name].get(taskflagname) or d.stamp[file_name]
+        extrainfo = d.stamp_extrainfo[file_name].get(taskflagname) or ""
+    else:
+        stamp = d.getVarFlag(taskflagname, 'stamp-base', True) or d.getVar('STAMP', True)
+        file_name = d.getVar('BB_FILENAME', True)
+        extrainfo = d.getVarFlag(taskflagname, 'stamp-extra-info', True) or ""
+
+    if baseonly:
+        return stamp
+
+    if not stamp:
+        return
+
+    stamp = bb.parse.siggen.stampfile(stamp, file_name, taskname, extrainfo)
+
+    stampdir = os.path.dirname(stamp)
+    if cached_mtime_noerror(stampdir) == 0:
+        bb.utils.mkdirhier(stampdir)
+
+    return stamp
+
+def stamp_cleanmask_internal(taskname, d, file_name):
+    """
+    Internal stamp helper function to generate stamp cleaning mask
+    Returns the stamp path+filename
+
+    In the bitbake core, d can be a CacheData and file_name will be set.
+    When called in task context, d will be a data store, file_name will not be set
+    """
+    taskflagname = taskname
+    if taskname.endswith("_setscene") and taskname != "do_setscene":
+        taskflagname = taskname.replace("_setscene", "")
+
+    if file_name:
+        stamp = d.stamp_base_clean[file_name].get(taskflagname) or d.stampclean[file_name]
+        extrainfo = d.stamp_extrainfo[file_name].get(taskflagname) or ""
+    else:
+        stamp = d.getVarFlag(taskflagname, 'stamp-base-clean', True) or d.getVar('STAMPCLEAN', True)
+        file_name = d.getVar('BB_FILENAME', True)
+        extrainfo = d.getVarFlag(taskflagname, 'stamp-extra-info', True) or ""
+
+    if not stamp:
+        return []
+
+    cleanmask = bb.parse.siggen.stampcleanmask(stamp, file_name, taskname, extrainfo)
+
+    return [cleanmask, cleanmask.replace(taskflagname, taskflagname + "_setscene")]
+
+def make_stamp(task, d, file_name = None):
+    """
+    Creates/updates a stamp for a given task
+    (d can be a data dict or dataCache)
+    """
+    cleanmask = stamp_cleanmask_internal(task, d, file_name)
+    for mask in cleanmask:
+        for name in glob.glob(mask):
+            # Preserve sigdata files in the stamps directory
+            if "sigdata" in name:
+                continue
+            # Preserve taint files in the stamps directory
+            if name.endswith('.taint'):
+                continue
+            os.unlink(name)
+
+    stamp = stamp_internal(task, d, file_name)
+    # Remove the file and recreate to force timestamp
+    # change on broken NFS filesystems
+    if stamp:
+        bb.utils.remove(stamp)
+        open(stamp, "w").close()
+
+    # If we're in task context, write out a signature file for each task
+    # as it completes
+    if not task.endswith("_setscene") and task != "do_setscene" and not file_name:
+        stampbase = stamp_internal(task, d, None, True)
+        file_name = d.getVar('BB_FILENAME', True)
+        bb.parse.siggen.dump_sigtask(file_name, task, stampbase, True)
+
+def del_stamp(task, d, file_name = None):
+    """
+    Removes a stamp for a given task
+    (d can be a data dict or dataCache)
+    """
+    stamp = stamp_internal(task, d, file_name)
+    bb.utils.remove(stamp)
+
+def write_taint(task, d, file_name = None):
+    """
+    Creates a "taint" file which will force the specified task and its
+    dependents to be re-run the next time by influencing the value of its
+    taskhash.
+    (d can be a data dict or dataCache)
+    """
+    import uuid
+    if file_name:
+        taintfn = d.stamp[file_name] + '.' + task + '.taint'
+    else:
+        taintfn = d.getVar('STAMP', True) + '.' + task + '.taint'
+    bb.utils.mkdirhier(os.path.dirname(taintfn))
+    # The specific content of the taint file is not really important,
+    # we just need it to be random, so a random UUID is used
+    with open(taintfn, 'w') as taintf:
+        taintf.write(str(uuid.uuid4()))
+
+def stampfile(taskname, d, file_name = None):
+    """
+    Return the stamp for a given task
+    (d can be a data dict or dataCache)
+    """
+    return stamp_internal(taskname, d, file_name)
+
+def add_tasks(tasklist, d):
+    task_deps = d.getVar('_task_deps', False)
+    if not task_deps:
+        task_deps = {}
+    if not 'tasks' in task_deps:
+        task_deps['tasks'] = []
+    if not 'parents' in task_deps:
+        task_deps['parents'] = {}
+
+    for task in tasklist:
+        task = d.expand(task)
+
+        d.setVarFlag(task, 'task', 1)
+
+        if not task in task_deps['tasks']:
+            task_deps['tasks'].append(task)
+
+        flags = d.getVarFlags(task)
+        def getTask(name):
+            if not name in task_deps:
+                task_deps[name] = {}
+            if name in flags:
+                deptask = d.expand(flags[name])
+                task_deps[name][task] = deptask
+        getTask('depends')
+        getTask('rdepends')
+        getTask('deptask')
+        getTask('rdeptask')
+        getTask('recrdeptask')
+        getTask('recideptask')
+        getTask('nostamp')
+        getTask('fakeroot')
+        getTask('noexec')
+        getTask('umask')
+        task_deps['parents'][task] = []
+        if 'deps' in flags:
+            for dep in flags['deps']:
+                dep = d.expand(dep)
+                task_deps['parents'][task].append(dep)
+
+    # don't assume holding a reference
+    d.setVar('_task_deps', task_deps)
+
+def addtask(task, before, after, d):
+    if task[:3] != "do_":
+        task = "do_" + task
+
+    d.setVarFlag(task, "task", 1)
+    bbtasks = d.getVar('__BBTASKS', False) or []
+    if task not in bbtasks:
+        bbtasks.append(task)
+    d.setVar('__BBTASKS', bbtasks)
+
+    existing = d.getVarFlag(task, "deps") or []
+    if after is not None:
+        # set up deps for function
+        for entry in after.split():
+            if entry not in existing:
+                existing.append(entry)
+    d.setVarFlag(task, "deps", existing)
+    if before is not None:
+        # set up things that depend on this func
+        for entry in before.split():
+            existing = d.getVarFlag(entry, "deps") or []
+            if task not in existing:
+                d.setVarFlag(entry, "deps", [task] + existing)
+
+def deltask(task, d):
+    if task[:3] != "do_":
+        task = "do_" + task
+
+    bbtasks = d.getVar('__BBTASKS', False) or []
+    if task in bbtasks:
+        bbtasks.remove(task)
+        d.setVar('__BBTASKS', bbtasks)
+
+    d.delVarFlag(task, 'deps')
+    for bbtask in d.getVar('__BBTASKS', False) or []:
+        deps = d.getVarFlag(bbtask, 'deps') or []
+        if task in deps:
+            deps.remove(task)
+            d.setVarFlag(bbtask, 'deps', deps)