3 files changed, 161 insertions, 3 deletions

diff --git a/scripts/lib/compatlayer/__init__.py b/scripts/lib/compatlayer/__init__.py
index 6130b8548c..0d6f4e9c3b 100644
--- a/scripts/lib/compatlayer/__init__.py
+++ b/scripts/lib/compatlayer/__init__.py
@@ -215,7 +215,7 @@ def check_command(error_msg, cmd):
         raise RuntimeError(msg)
     return output
 
-def get_signatures(builddir, failsafe=False):
+def get_signatures(builddir, failsafe=False, machine=None):
     import re
 
     # some recipes needs to be excluded like meta-world-pkgdata
@@ -226,7 +226,10 @@ def get_signatures(builddir, failsafe=False):
     sigs = {}
     tune2tasks = {}
 
-    cmd = 'bitbake '
+    cmd = ''
+    if machine:
+        cmd += 'MACHINE=%s ' % machine
+    cmd += 'bitbake '
     if failsafe:
         cmd += '-k '
     cmd += '-S none world'
diff --git a/scripts/lib/compatlayer/cases/bsp.py b/scripts/lib/compatlayer/cases/bsp.py
index 5d9bf93e4a..90256750af 100644
--- a/scripts/lib/compatlayer/cases/bsp.py
+++ b/scripts/lib/compatlayer/cases/bsp.py
@@ -3,7 +3,7 @@
 
 import unittest
 
-from compatlayer import LayerType
+from compatlayer import LayerType, get_signatures, check_command, get_depgraph
 from compatlayer.case import OECompatLayerTestCase
 
 class BSPCompatLayer(OECompatLayerTestCase):
@@ -24,3 +24,155 @@ class BSPCompatLayer(OECompatLayerTestCase):
         self.assertEqual(self.td['bbvars']['MACHINE'], machine,
                 msg="Layer %s modified machine %s -> %s" % \
                     (self.tc.layer['name'], self.td['bbvars']['MACHINE'], machine))
+
+    def test_machine_signatures(self):
+        '''
+        Selecting a machine may only affect the signature of tasks that are specific
+        to that machine. In other words, when MACHINE=A and MACHINE=B share a recipe
+        foo and the output of foo, then both machine configurations must build foo
+        in exactly the same way. Otherwise it is not possible to use both machines
+        in the same distribution.
+
+        This criteria can only be tested by testing different machines in combination,
+        i.e. one main layer, potentially several additional BSP layers and an explicit
+        choice of machines:
+        yocto-compat-layer --additional-layers .../meta-intel --machines intel-corei7-64 imx6slevk -- .../meta-freescale
+        '''
+
+        if not self.td['machines']:
+            self.skipTest('No machines set with --machines.')
+
+        # Collect signatures for all machines that we are testing
+        # and merge that into a hash:
+        # tune -> task -> signature -> list of machines with that combination
+        #
+        # It is an error if any tune/task pair has more than one signature,
+        # because that implies that the machines that caused those different
+        # signatures do not agree on how to execute the task.
+        tunes = {}
+        # Preserve ordering of machines as chosen by the user.
+        for machine in self.td['machines']:
+            curr_sigs, tune2tasks = get_signatures(self.td['builddir'], failsafe=True, machine=machine)
+            # Invert the tune -> [tasks] mapping.
+            tasks2tune = {}
+            for tune, tasks in tune2tasks.items():
+                for task in tasks:
+                    tasks2tune[task] = tune
+            for task, sighash in curr_sigs.items():
+                tunes.setdefault(tasks2tune[task], {}).setdefault(task, {}).setdefault(sighash, []).append(machine)
+
+        msg = []
+        pruned = 0
+        last_line_key = None
+        # do_fetch, do_unpack, ..., do_build
+        taskname_list = []
+        if tunes:
+            # The output below is most useful when we start with tasks that are at
+            # the bottom of the dependency chain, i.e. those that run first. If
+            # those tasks differ, the rest also does.
+            #
+            # To get an ordering of tasks, we do a topological sort of the entire
+            # depgraph for the base configuration, then on-the-fly flatten that list by stripping
+            # out the recipe names and removing duplicates. The base configuration
+            # is not necessarily representative, but should be close enough. Tasks
+            # that were not encountered get a default priority.
+            depgraph = get_depgraph()
+            depends = depgraph['tdepends']
+            WHITE = 1
+            GRAY = 2
+            BLACK = 3
+            color = {}
+            found = set()
+            def visit(task):
+                color[task] = GRAY
+                for dep in depends.get(task, ()):
+                    if color.setdefault(dep, WHITE) == WHITE:
+                        visit(dep)
+                color[task] = BLACK
+                pn, taskname = task.rsplit('.', 1)
+                if taskname not in found:
+                    taskname_list.append(taskname)
+                    found.add(taskname)
+            for task in depends.keys():
+                if color.setdefault(task, WHITE) == WHITE:
+                    visit(task)
+
+        taskname_order = dict([(task, index) for index, task in enumerate(taskname_list) ])
+        def task_key(task):
+            pn, taskname = task.rsplit(':', 1)
+            return (pn, taskname_order.get(taskname, len(taskname_list)), taskname)
+
+        for tune in sorted(tunes.keys()):
+            tasks = tunes[tune]
+            # As for test_signatures it would be nicer to sort tasks
+            # by dependencies here, but that is harder because we have
+            # to report on tasks from different machines, which might
+            # have different dependencies. We resort to pruning the
+            # output by reporting only one task per recipe if the set
+            # of machines matches.
+            #
+            # "bitbake-diffsigs -t -s" is intelligent enough to print
+            # diffs recursively, so often it does not matter that much
+            # if we don't pick the underlying difference
+            # here. However, sometimes recursion fails
+            # (https://bugzilla.yoctoproject.org/show_bug.cgi?id=6428).
+            #
+            # To mitigate that a bit, we use a hard-coded ordering of
+            # tasks that represents how they normally run and prefer
+            # to print the ones that run first.
+            for task in sorted(tasks.keys(), key=task_key):
+                signatures = tasks[task]
+                # do_build can be ignored: it is know to have
+                # different signatures in some cases, for example in
+                # the allarch ca-certificates due to RDEPENDS=openssl.
+                # That particular dependency is whitelisted via
+                # SIGGEN_EXCLUDE_SAFE_RECIPE_DEPS, but still shows up
+                # in the sstate signature hash because filtering it
+                # out would be hard and running do_build multiple
+                # times doesn't really matter.
+                if len(signatures.keys()) > 1 and \
+                   not task.endswith(':do_build'):
+                    # Error!
+                    #
+                    # Sort signatures by machines, because the hex values don't mean anything.
+                    # => all-arch adwaita-icon-theme:do_build: 1234... (beaglebone, qemux86) != abcdf... (qemux86-64)
+                    #
+                    # Skip the line if it is covered already by the predecessor (same pn, same sets of machines).
+                    pn, taskname = task.rsplit(':', 1)
+                    next_line_key = (pn, sorted(signatures.values()))
+                    if next_line_key != last_line_key:
+                        line = '   %s %s: ' % (tune, task)
+                        line += ' != '.join(['%s (%s)' % (signature, ', '.join([m for m in signatures[signature]])) for
+                                             signature in sorted(signatures.keys(), key=lambda s: signatures[s])])
+                        last_line_key = next_line_key
+                        msg.append(line)
+                        # Randomly pick two mismatched signatures and remember how to invoke
+                        # bitbake-diffsigs for them.
+                        iterator = iter(signatures.items())
+                        a = next(iterator)
+                        b = next(iterator)
+                        diffsig_machines = '(%s) != (%s)' % (', '.join(a[1]), ', '.join(b[1]))
+                        diffsig_params = '-t %s %s -s %s %s' % (pn, taskname, a[0], b[0])
+                    else:
+                        pruned += 1
+
+        if msg:
+            msg.insert(0, 'The machines have conflicting signatures for some shared tasks:')
+            if pruned > 0:
+                msg.append('')
+                msg.append('%d tasks where not listed because some other task of the recipe already differed.' % pruned)
+                msg.append('It is likely that differences from different recipes also have the same root cause.')
+            msg.append('')
+            # Explain how to investigate...
+            msg.append('To investigate, run bitbake-diffsigs -t recipename taskname -s fromsig tosig.')
+            cmd = 'bitbake-diffsigs %s' % diffsig_params
+            msg.append('Example: %s in the last line' % diffsig_machines)
+            msg.append('Command: %s' % cmd)
+            # ... and actually do it automatically for that example, but without aborting
+            # when that fails.
+            try:
+                output = check_command('Comparing signatures failed.', cmd).decode('utf-8')
+            except RuntimeError as ex:
+                output = str(ex)
+            msg.extend(['   ' + line for line in output.splitlines()])
+            self.fail('\n'.join(msg))
diff --git a/scripts/yocto-compat-layer.py b/scripts/yocto-compat-layer.py
index daf3a6a32a..0d5700b538 100755
--- a/scripts/yocto-compat-layer.py
+++ b/scripts/yocto-compat-layer.py
@@ -49,6 +49,8 @@ def main():
             help='File to output log (optional)', action='store')
     parser.add_argument('--dependency', nargs="+",
             help='Layers to process for dependencies', action='store')
+    parser.add_argument('--machines', nargs="+",
+            help='List of MACHINEs to be used during testing', action='store')
     parser.add_argument('--additional-layers', nargs="+",
             help='List of additional layers to add during testing', action='store')
     parser.add_argument('-n', '--no-auto', help='Disable auto layer discovery',
@@ -162,6 +164,7 @@ def main():
         logger.info('Getting initial signatures ...')
         td['builddir'] = builddir
         td['sigs'], td['tunetasks'] = get_signatures(td['builddir'])
+        td['machines'] = args.machines
 
         if not add_layer(bblayersconf, layer, dep_layers, logger):
             logger.info('Skipping %s ???.' % layer['name'])