diff --git a/tools/buildman/README b/tools/buildman/README
index 4cf0114..f3a0dc7 100644
--- a/tools/buildman/README
+++ b/tools/buildman/README
@@ -51,23 +51,25 @@
 
 Buildman is a builder. It is not make, although it runs make. It does not
 produce any useful output on the terminal while building, except for
-progress information (except with -v, see below). All the output (errors,
-warnings and binaries if you ask for them) is stored in output
-directories, which you can look at while the build is progressing, or when
-it is finished.
+progress information (but see -v below). All the output (errors, warnings and
+binaries if you ask for them) is stored in output directories, which you can
+look at from a separate 'buildman -s' instance while the build is progressing,
+or when it is finished.
 
 Buildman is designed to build entire git branches, i.e. muliple commits. It
-can be run repeatedly on the same branch. In this case it will automatically
-rebuild commits which have changed (and remove its old results for that
-commit). It is possible to build a branch for one board, then later build it
-for another board. If you want buildman to re-build a commit it has already
-built (e.g. because of a toolchain update), use the -f flag.
+can be run repeatedly on the same branch after making changes to commits on
+that branch. In this case it will automatically rebuild commits which have
+changed (and remove its old results for that commit). It is possible to build
+a branch for one board, then later build it for another board. This adds to
+the output, so now you have results for two boards. If you want buildman to
+re-build a commit it has already built (e.g. because of a toolchain update),
+use the -f flag.
 
 Buildman produces a concise summary of which boards succeeded and failed.
 It shows which commit introduced which board failure using a simple
-red/green colour coding. Full error information can be requested, in which
-case it is de-duped and displayed against the commit that introduced the
-error. An example workflow is below.
+red/green colour coding (with yellow/cyan for warnings). Full error
+information can be requested, in which case it is de-duped and displayed
+against the commit that introduced the error. An example workflow is below.
 
 Buildman stores image size information and can report changes in image size
 from commit to commit. An example of this is below.
@@ -75,16 +77,20 @@
 Buildman starts multiple threads, and each thread builds for one board at
 a time. A thread starts at the first commit, configures the source for your
 board and builds it. Then it checks out the next commit and does an
-incremental build. Eventually the thread reaches the last commit and stops.
-If errors or warnings are found along the way, the thread will reconfigure
-after every commit, and your build will be very slow. This is because a
-file that produces just a warning would not normally be rebuilt in an
-incremental build.
+incremental build (i.e. not using 'make xxx_defconfig' unless you use -C).
+Eventually the thread reaches the last commit and stops. If a commit causes
+an error or warning, buildman will try it again after reconfiguring (but see
+-Q). Thus some commits may be built twice, with the first result silently
+discarded. Lots of errors and warnings will causes lots of reconfigures and your
+build will be very slow. This is because a file that produces just a warning
+would not normally be rebuilt in an incremental build. Once a thread finishes
+building all the commits for a board, it starts on the commits for another
+board.
 
 Buildman works in an entirely separate place from your U-Boot repository.
 It creates a separate working directory for each thread, and puts the
 output files in the working directory, organised by commit name and board
-name, in a two-level hierarchy.
+name, in a two-level hierarchy (but see -P).
 
 Buildman is invoked in your U-Boot directory, the one with the .git
 directory. It clones this repository into a copy for each thread, and the
@@ -92,20 +98,23 @@
 by the thread affect only the working directory for that thread.
 
 Buildman automatically selects the correct tool chain for each board. You
-must supply suitable tool chains, but buildman takes care of selecting the
-right one.
+must supply suitable tool chains (see --fetch-arch), but buildman takes care
+of selecting the right one.
 
 Buildman generally builds a branch (with the -b flag), and in this case
-builds the upstream commit as well, for comparison. It cannot build
-individual commits at present, unless (maybe) you point it at an empty
-branch. Put all your commits in a branch, set the branch's upstream to a
-valid value, and all will be well. Otherwise buildman will perform random
-actions. Use -n to check what the random actions might be.
+builds the upstream commit as well, for comparison. So even if you have one
+commit in your branch, two commits will be built. Put all your commits in a
+branch, set the branch's upstream to a valid value, and all will be well.
+Otherwise buildman will perform random actions. Use -n to check what the
+random actions might be.
+
+Buildman effectively has two modes: without -s it builds, with -s it
+summarises the results of previous (or active) builds.
 
-If you just want to build the current source tree, leave off the -b flag
-and add -e. This will display results and errors as they happen. You can
-still look at them later using -se. Note that buildman will assume that the
-source has changed, and will build all specified boards in this case.
+If you just want to build the current source tree, leave off the -b flag.
+This will display results and errors as they happen. You can still look at
+them later using -se. Note that buildman will assume that the source has
+changed, and will build all specified boards in this case.
 
 Buildman is optimised for building many commits at once, for many boards.
 On multi-core machines, Buildman is fast because it uses most of the
@@ -142,9 +151,9 @@
 means to build all arm boards except nvidia, freescale and anything ending
 with 'ball'.
 
-For building specific boards you can use the --boards option, which takes a
-comma-separated list of board target names and be used multiple times on
-the command line:
+For building specific boards you can use the --boards (or --bo) option, which
+takes a comma-separated list of board target names and be used multiple times
+on the command line:
 
   buildman --boards sandbox,snow --boards
 
@@ -492,6 +501,8 @@
 doing something like 'git branch --set-upstream-to upstream/master'
 or something similar. Buildman will try to guess a suitable upstream branch
 if it can't find one (you will see a message like" Guessing upstream as ...).
+You can also use the -c option to manually specify the number of commits to
+build.
 
 As an example:
 
@@ -542,12 +553,13 @@
 minute or so it will settle down to a steady pace, with a display like this:
 
 Building 18 commits for 1059 boards (4 threads, 1 job per thread)
-  528   36  124 /19062  1:13:30  : SIMPC8313_SP
+  528   36  124 /19062    -18374  1:13:30  : SIMPC8313_SP
 
 This means that it is building 19062 board/commit combinations. So far it
 has managed to successfully build 528. Another 36 have built with warnings,
-and 124 more didn't build at all. Buildman expects to complete the process
-in around an hour and a quarter. Use this time to buy a faster computer.
+and 124 more didn't build at all. It has 18374 builds left to complete.
+Buildman expects to complete the process in around an hour and a quarter.
+Use this time to buy a faster computer.
 
 
 To find out how the build went, ask for a summary with -s. You can do this
@@ -579,32 +591,32 @@
 
 This shows which commits have succeeded and which have failed. In this case
 the build is still in progress so many boards are not built yet (use -u to
-see which ones). But still we can see a few failures. The galaxy5200_LOWBOOT
+see which ones). But already we can see a few failures. The galaxy5200_LOWBOOT
 never builds correctly. This could be a problem with our toolchain, or it
 could be a bug in the upstream. The good news is that we probably don't need
 to blame our commits. The bad news is that our commits are not tested on that
 board.
 
-Commit 12 broke lubbock. That's what the '+ lubbock' means. The failure
-is never fixed by a later commit, or you would see lubbock again, in green,
-without the +.
+Commit 12 broke lubbock. That's what the '+ lubbock', in red, means. The
+failure is never fixed by a later commit, or you would see lubbock again, in
+green, without the +.
 
 To see the actual error:
 
-$ ./tools/buildman/buildman -b <branch> -se lubbock
+$ ./tools/buildman/buildman -b <branch> -se
 ...
 12: lcd: Add support for flushing LCD fb from dcache after update
        arm:   + lubbock
 +common/libcommon.o: In function `lcd_sync':
-+/u-boot/lcd9b/.bm-work/00/common/lcd.c:120: undefined reference to `flush_dcache_range'
++common/lcd.c:120: undefined reference to `flush_dcache_range'
 +arm-none-linux-gnueabi-ld: BFD (Sourcery G++ Lite 2010q1-202) 2.19.51.20090709 assertion fail /scratch/julian/2010q1-release-linux-lite/obj/binutils-src-2010q1-202-arm-none-linux-gnueabi-i686-pc-linux-gnu/bfd/elf32-arm.c:12572
-+make: *** [/u-boot/lcd9b/.bm-work/00/build/u-boot] Error 139
++make: *** [build/u-boot] Error 139
 13: tegra: Align LCD frame buffer to section boundary
 14: tegra: Support control of cache settings for LCD
 15: tegra: fdt: Add LCD definitions for Seaboard
 16: lcd: Add CONFIG_CONSOLE_SCROLL_LINES option to speed console
--/u-boot/lcd9b/.bm-work/00/common/lcd.c:120: undefined reference to `flush_dcache_range'
-+/u-boot/lcd9b/.bm-work/00/common/lcd.c:125: undefined reference to `flush_dcache_range'
+-common/lcd.c:120: undefined reference to `flush_dcache_range'
++common/lcd.c:125: undefined reference to `flush_dcache_range'
 17: tegra: Enable display/lcd support on Seaboard
 18: wip
 
@@ -612,6 +624,21 @@
 should be enough to work out what that commit is doing to break these
 boards. (In this case pxa did not have cache operations defined).
 
+Note that if there were other boards with errors, the above command would
+show their errors also. Each line is shown only once. So if lubbock and snow
+produce the same error, we just see:
+
+12: lcd: Add support for flushing LCD fb from dcache after update
+       arm:   + lubbock snow
++common/libcommon.o: In function `lcd_sync':
++common/lcd.c:120: undefined reference to `flush_dcache_range'
++arm-none-linux-gnueabi-ld: BFD (Sourcery G++ Lite 2010q1-202) 2.19.51.20090709 assertion fail /scratch/julian/2010q1-release-linux-lite/obj/binutils-src-2010q1-202-arm-none-linux-gnueabi-i686-pc-linux-gnu/bfd/elf32-arm.c:12572
++make: *** [build/u-boot] Error 139
+
+But if you did want to see just the errors for lubbock, use:
+
+$ ./tools/buildman/buildman -b <branch> -se lubbock
+
 If you see error lines marked with '-', that means that the errors were fixed
 by that commit. Sometimes commits can be in the wrong order, so that a
 breakage is introduced for a few commits and fixed by later commits. This
@@ -622,13 +649,14 @@
 is fixed, but there is a new one at line 126. This is probably only because
 we added some code and moved the broken line further down the file.
 
-If many boards have the same error, then -e will display the error only
-once. This makes the output as concise as possible. To see which boards have
-each error, use -l. So it is safe to omit the board name - you will not get
-lots of repeated output for every board.
+As mentioned, if many boards have the same error, then -e will display the
+error only once. This makes the output as concise as possible. To see which
+boards have each error, use -l. So it is safe to omit the board name - you
+will not get lots of repeated output for every board.
 
 Buildman tries to distinguish warnings from errors, and shows warning lines
-separately with a 'w' prefix.
+separately with a 'w' prefix. Warnings introduced show as yellow. Warnings
+fixed show as cyan.
 
 The full build output in this case is available in:
 
@@ -930,12 +958,11 @@
 Building Faster
 ===============
 
-By default, buildman executes 'make mrproper' prior to building the first
-commit for each board. This causes everything to be built from scratch. If you
-trust the build system's incremental build capabilities, you can pass the -I
-flag to skip the 'make mproper' invocation, which will reduce the amount of
-work 'make' does, and hence speed up the build. This flag will speed up any
-buildman invocation, since it reduces the amount of work done on any build.
+By default, buildman doesn't execute 'make mrproper' prior to building the
+first commit for each board. This reduces the amount of work 'make' does, and
+hence speeds up the build. To force use of 'make mrproper', use -the -m flag.
+This flag will slow down any buildman invocation, since it increases the amount
+of work done on any build.
 
 One possible application of buildman is as part of a continual edit, build,
 edit, build, ... cycle; repeatedly applying buildman to the same change or
@@ -966,7 +993,7 @@
 This will provide the quickest possible feedback regarding the current content
 of the source tree, thus allowing rapid tested evolution of the code.
 
-    SOURCE_DATE_EPOCH=0 ./tools/buildman/buildman -I -P tegra
+    SOURCE_DATE_EPOCH=0 ./tools/buildman/buildman -P tegra
 
 
 Checking configuration
@@ -1087,16 +1114,19 @@
 When doing builds, Buildman's return code will reflect the overall result:
 
     0 (success)     No errors or warnings found
-    128             Errors found
-    129             Warnings found (only if no -W)
+    100             Errors found
+    101             Warnings found (only if no -W)
 
-You can use -W to tell Buildman to return 0 (success) instead of 129 when
+You can use -W to tell Buildman to return 0 (success) instead of 101 when
 warnings are found. Note that it can be useful to combine -E and -W. This means
-that all compiler warnings will produce failures (code 128) and all other
-warnings will produce success (since 129 is changed to 0).
+that all compiler warnings will produce failures (code 100) and all other
+warnings will produce success (since 101 is changed to 0).
 
-If there are both warnings and errors, errors win, so buildman returns 128.
+If there are both warnings and errors, errors win, so buildman returns 100.
 
+The -y option is provided (for use with -s) to ignore the bountiful device-tree
+warnings. Similarly, -Y tells buildman to ignore the migration warnings.
+
 
 How to change from MAKEALL
 ==========================
@@ -1202,13 +1232,17 @@
 TODO
 ====
 
-This has mostly be written in my spare time as a response to my difficulties
-in testing large series of patches. Apart from tidying up there is quite a
-bit of scope for improvement. Things like better error diffs and easier
-access to log files. Also it would be nice if buildman could 'hunt' for
-problems, perhaps by building a few boards for each arch, or checking
-commits for changed files and building only boards which use those files.
+Many improvements have been made over the years. There is still quite a bit of
+scope for more though, e.g.:
 
+- easier access to log files
+- 'hunting' for problems, perhaps by building a few boards for each arch, or
+  checking commits for changed files and building only boards which use those
+  files
+- using the same git repo for all threads instead of cloning it. Currently
+  it uses about 500MB per thread, so on a 64-thread machine this is 32GB for
+  the build.
+
 
 Credits
 =======
@@ -1223,3 +1257,4 @@
 Halloween 2012
 Updated 12-12-12
 Updated 23-02-13
+Updated 09-04-20
diff --git a/tools/buildman/builder.py b/tools/buildman/builder.py
index 70c55c5..30ebe1d 100644
--- a/tools/buildman/builder.py
+++ b/tools/buildman/builder.py
@@ -24,7 +24,6 @@
 from terminal import Print
 import toolchain
 
-
 """
 Theory of Operation
 
@@ -91,6 +90,15 @@
     .git/           repository
 """
 
+"""Holds information about a particular error line we are outputing
+
+   char: Character representation: '+': error, '-': fixed error, 'w+': warning,
+       'w-' = fixed warning
+   boards: List of Board objects which have line in the error/warning output
+   errline: The text of the error line
+"""
+ErrLine = collections.namedtuple('ErrLine', 'char,boards,errline')
+
 # Possible build outcomes
 OUTCOME_OK, OUTCOME_WARNING, OUTCOME_ERROR, OUTCOME_UNKNOWN = list(range(4))
 
@@ -154,8 +162,6 @@
         force_build_failures: If a previously-built build (i.e. built on
             a previous run of buildman) is marked as failed, rebuild it.
         git_dir: Git directory containing source repository
-        last_line_len: Length of the last line we printed (used for erasing
-            it with new progress information)
         num_jobs: Number of jobs to run at once (passed to make as -j)
         num_threads: Number of builder threads to run
         out_queue: Queue of results to process
@@ -186,6 +192,7 @@
         _next_delay_update: Next time we plan to display a progress update
                 (datatime)
         _show_unknown: Show unknown boards (those not built) in summary
+        _start_time: Start time for the build
         _timestamps: List of timestamps for the completion of the last
             last _timestamp_count builds. Each is a datetime object.
         _timestamp_count: Number of timestamps to keep in our list.
@@ -224,7 +231,7 @@
     def __init__(self, toolchains, base_dir, git_dir, num_threads, num_jobs,
                  gnu_make='make', checkout=True, show_unknown=True, step=1,
                  no_subdirs=False, full_path=False, verbose_build=False,
-                 incremental=False, per_board_out_dir=False,
+                 mrproper=False, per_board_out_dir=False,
                  config_only=False, squash_config_y=False,
                  warnings_as_errors=False, work_in_output=False):
         """Create a new Builder object
@@ -245,8 +252,7 @@
             full_path: Return the full path in CROSS_COMPILE and don't set
                 PATH
             verbose_build: Run build with V=1 and don't use 'make -s'
-            incremental: Always perform incremental builds; don't run make
-                mrproper when configuring
+            mrproper: Always run 'make mrproper' when configuring
             per_board_out_dir: Build in a separate persistent directory per
                 board rather than a thread-specific directory
             config_only: Only configure each build, don't build it
@@ -275,6 +281,7 @@
         self._build_period_us = None
         self._complete_delay = None
         self._next_delay_update = datetime.now()
+        self._start_time = datetime.now()
         self.force_config_on_failure = True
         self.force_build_failures = False
         self.force_reconfig = False
@@ -299,17 +306,18 @@
         self._re_warning = re.compile('(.*):(\d*):(\d*): warning: .*')
         self._re_dtb_warning = re.compile('(.*): Warning .*')
         self._re_note = re.compile('(.*):(\d*):(\d*): note: this is the location of the previous.*')
+        self._re_migration_warning = re.compile(r'^={21} WARNING ={22}\n.*\n=+\n',
+                                                re.MULTILINE | re.DOTALL)
 
         self.queue = queue.Queue()
         self.out_queue = queue.Queue()
         for i in range(self.num_threads):
-            t = builderthread.BuilderThread(self, i, incremental,
+            t = builderthread.BuilderThread(self, i, mrproper,
                     per_board_out_dir)
             t.setDaemon(True)
             t.start()
             self.threads.append(t)
 
-        self.last_line_len = 0
         t = builderthread.ResultThread(self)
         t.setDaemon(True)
         t.start()
@@ -332,16 +340,22 @@
     def SetDisplayOptions(self, show_errors=False, show_sizes=False,
                           show_detail=False, show_bloat=False,
                           list_error_boards=False, show_config=False,
-                          show_environment=False):
+                          show_environment=False, filter_dtb_warnings=False,
+                          filter_migration_warnings=False):
         """Setup display options for the builder.
 
-        show_errors: True to show summarised error/warning info
-        show_sizes: Show size deltas
-        show_detail: Show size delta detail for each board if show_sizes
-        show_bloat: Show detail for each function
-        list_error_boards: Show the boards which caused each error/warning
-        show_config: Show config deltas
-        show_environment: Show environment deltas
+        Args:
+            show_errors: True to show summarised error/warning info
+            show_sizes: Show size deltas
+            show_detail: Show size delta detail for each board if show_sizes
+            show_bloat: Show detail for each function
+            list_error_boards: Show the boards which caused each error/warning
+            show_config: Show config deltas
+            show_environment: Show environment deltas
+            filter_dtb_warnings: Filter out any warnings from the device-tree
+                compiler
+            filter_migration_warnings: Filter out any warnings about migrating
+                a board to driver model
         """
         self._show_errors = show_errors
         self._show_sizes = show_sizes
@@ -350,6 +364,8 @@
         self._list_error_boards = list_error_boards
         self._show_config = show_config
         self._show_environment = show_environment
+        self._filter_dtb_warnings = filter_dtb_warnings
+        self._filter_migration_warnings = filter_migration_warnings
 
     def _AddTimestamp(self):
         """Add a new timestamp to the list and record the build period.
@@ -380,22 +396,6 @@
             self._timestamps.popleft()
             count -= 1
 
-    def ClearLine(self, length):
-        """Clear any characters on the current line
-
-        Make way for a new line of length 'length', by outputting enough
-        spaces to clear out the old line. Then remember the new length for
-        next time.
-
-        Args:
-            length: Length of new line, in characters
-        """
-        if length < self.last_line_len:
-            Print(' ' * (self.last_line_len - length), newline=False)
-            Print('\r', newline=False)
-        self.last_line_len = length
-        sys.stdout.flush()
-
     def SelectCommit(self, commit, checkout=True):
         """Checkout the selected commit for this build
         """
@@ -441,8 +441,7 @@
             if result.already_done:
                 self.already_done += 1
             if self._verbose:
-                Print('\r', newline=False)
-                self.ClearLine(0)
+                terminal.PrintClear()
                 boards_selected = {target : result.brd}
                 self.ResetResultSummary(boards_selected)
                 self.ProduceResultSummary(result.commit_upto, self.commits,
@@ -456,22 +455,21 @@
         line += self.col.Color(self.col.YELLOW, '%5d' % self.warned)
         line += self.col.Color(self.col.RED, '%5d' % self.fail)
 
-        name = ' /%-5d  ' % self.count
+        line += ' /%-5d  ' % self.count
+        remaining = self.count - self.upto
+        if remaining:
+            line += self.col.Color(self.col.MAGENTA, ' -%-5d  ' % remaining)
+        else:
+            line += ' ' * 8
 
         # Add our current completion time estimate
         self._AddTimestamp()
         if self._complete_delay:
-            name += '%s  : ' % self._complete_delay
-        # When building all boards for a commit, we can print a commit
-        # progress message.
-        if result and result.commit_upto is None:
-            name += 'commit %2d/%-3d' % (self.commit_upto + 1,
-                    self.commit_count)
+            line += '%s  : ' % self._complete_delay
 
-        name += target
-        Print(line + name, newline=False)
-        length = 16 + len(name)
-        self.ClearLine(length)
+        line += target
+        terminal.PrintClear()
+        Print(line, newline=False, limit_to_line=True)
 
     def _GetOutputDir(self, commit_upto):
         """Get the name of the output directory for a commit number
@@ -567,9 +565,16 @@
             New list with only interesting lines included
         """
         out_lines = []
+        if self._filter_migration_warnings:
+            text = '\n'.join(lines)
+            text = self._re_migration_warning.sub('', text)
+            lines = text.splitlines()
         for line in lines:
-            if not self.re_make_err.search(line):
-                out_lines.append(line)
+            if self.re_make_err.search(line):
+                continue
+            if self._filter_dtb_warnings and self._re_dtb_warning.search(line):
+                continue
+            out_lines.append(line)
         return out_lines
 
     def ReadFuncSizes(self, fname, fd):
@@ -1128,32 +1133,52 @@
 
             Args:
                 line: Error line to search for
+                line_boards: boards to search, each a Board
             Return:
-                String containing a list of boards with that error line, or
-                '' if the user has not requested such a list
+                List of boards with that error line, or [] if the user has not
+                    requested such a list
             """
+            boards = []
+            board_set = set()
             if self._list_error_boards:
-                names = []
                 for board in line_boards[line]:
-                    if not board.target in names:
-                        names.append(board.target)
-                names_str = '(%s) ' % ','.join(names)
-            else:
-                names_str = ''
-            return names_str
+                    if not board in board_set:
+                        boards.append(board)
+                        board_set.add(board)
+            return boards
 
         def _CalcErrorDelta(base_lines, base_line_boards, lines, line_boards,
                             char):
+            """Calculate the required output based on changes in errors
+
+            Args:
+                base_lines: List of errors/warnings for previous commit
+                base_line_boards: Dict keyed by error line, containing a list
+                    of the Board objects with that error in the previous commit
+                lines: List of errors/warning for this commit, each a str
+                line_boards: Dict keyed by error line, containing a list
+                    of the Board objects with that error in this commit
+                char: Character representing error ('') or warning ('w'). The
+                    broken ('+') or fixed ('-') characters are added in this
+                    function
+
+            Returns:
+                Tuple
+                    List of ErrLine objects for 'better' lines
+                    List of ErrLine objects for 'worse' lines
+            """
             better_lines = []
             worse_lines = []
             for line in lines:
                 if line not in base_lines:
-                    worse_lines.append(char + '+' +
-                            _BoardList(line, line_boards) + line)
+                    errline = ErrLine(char + '+', _BoardList(line, line_boards),
+                                      line)
+                    worse_lines.append(errline)
             for line in base_lines:
                 if line not in lines:
-                    better_lines.append(char + '-' +
-                            _BoardList(line, base_line_boards) + line)
+                    errline = ErrLine(char + '-',
+                                      _BoardList(line, base_line_boards), line)
+                    better_lines.append(errline)
             return better_lines, worse_lines
 
         def _CalcConfig(delta, name, config):
@@ -1209,6 +1234,34 @@
                     col = self.col.YELLOW
                 Print('   ' + line, newline=True, colour=col)
 
+        def _OutputErrLines(err_lines, colour):
+            """Output the line of error/warning lines, if not empty
+
+            Also increments self._error_lines if err_lines not empty
+
+            Args:
+                err_lines: List of ErrLine objects, each an error or warning
+                    line, possibly including a list of boards with that
+                    error/warning
+                colour: Colour to use for output
+            """
+            if err_lines:
+                out_list = []
+                for line in err_lines:
+                    boards = ''
+                    names = [board.target for board in line.boards]
+                    board_str = ' '.join(names) if names else ''
+                    if board_str:
+                        out = self.col.Color(colour, line.char + '(')
+                        out += self.col.Color(self.col.MAGENTA, board_str,
+                                              bright=False)
+                        out += self.col.Color(colour, ') %s' % line.errline)
+                    else:
+                        out = self.col.Color(colour, line.char + line.errline)
+                    out_list.append(out)
+                Print('\n'.join(out_list))
+                self._error_lines += 1
+
 
         ok_boards = []      # List of boards fixed since last commit
         warn_boards = []    # List of boards with warnings since last commit
@@ -1239,7 +1292,7 @@
             else:
                 new_boards.append(target)
 
-        # Get a list of errors that have appeared, and disappeared
+        # Get a list of errors and warnings that have appeared, and disappeared
         better_err, worse_err = _CalcErrorDelta(self._base_err_lines,
                 self._base_err_line_boards, err_lines, err_line_boards, '')
         better_warn, worse_warn = _CalcErrorDelta(self._base_warn_lines,
@@ -1262,18 +1315,10 @@
             for arch, target_list in arch_list.items():
                 Print('%10s: %s' % (arch, target_list))
                 self._error_lines += 1
-            if better_err:
-                Print('\n'.join(better_err), colour=self.col.GREEN)
-                self._error_lines += 1
-            if worse_err:
-                Print('\n'.join(worse_err), colour=self.col.RED)
-                self._error_lines += 1
-            if better_warn:
-                Print('\n'.join(better_warn), colour=self.col.CYAN)
-                self._error_lines += 1
-            if worse_warn:
-                Print('\n'.join(worse_warn), colour=self.col.MAGENTA)
-                self._error_lines += 1
+            _OutputErrLines(better_err, colour=self.col.GREEN)
+            _OutputErrLines(worse_err, colour=self.col.RED)
+            _OutputErrLines(better_warn, colour=self.col.CYAN)
+            _OutputErrLines(worse_warn, colour=self.col.YELLOW)
 
         if show_sizes:
             self.PrintSizeSummary(board_selected, board_dict, show_detail,
@@ -1506,12 +1551,15 @@
         if setup_git and self.git_dir:
             src_dir = os.path.abspath(self.git_dir)
             if os.path.exists(git_dir):
+                Print('\rFetching repo for thread %d' % thread_num,
+                      newline=False)
                 gitutil.Fetch(git_dir, thread_dir)
+                terminal.PrintClear()
             else:
                 Print('\rCloning repo for thread %d' % thread_num,
                       newline=False)
                 gitutil.Clone(src_dir, thread_dir)
-                Print('\r%s\r' % (' ' * 30), newline=False)
+                terminal.PrintClear()
 
     def _PrepareWorkingSpace(self, max_threads, setup_git):
         """Prepare the working directory for use.
@@ -1564,7 +1612,7 @@
                   newline=False)
             for dirname in to_remove:
                 shutil.rmtree(dirname)
-            Print('done')
+            terminal.PrintClear()
 
     def BuildBoards(self, commits, board_selected, keep_outputs, verbose):
         """Build all commits for a list of boards
@@ -1612,5 +1660,19 @@
         # Wait until we have processed all output
         self.out_queue.join()
         Print()
-        self.ClearLine(0)
+
+        msg = 'Completed: %d total built' % self.count
+        if self.already_done:
+           msg += ' (%d previously' % self.already_done
+           if self.already_done != self.count:
+               msg += ', %d newly' % (self.count - self.already_done)
+           msg += ')'
+        duration = datetime.now() - self._start_time
+        if duration > timedelta(microseconds=1000000):
+            if duration.microseconds >= 500000:
+                duration = duration + timedelta(seconds=1)
+            duration = duration - timedelta(microseconds=duration.microseconds)
+            msg += ', duration %s' % duration
+        Print(msg)
+
         return (self.fail, self.warned)
diff --git a/tools/buildman/builderthread.py b/tools/buildman/builderthread.py
index 7561f39..fc6e1ab 100644
--- a/tools/buildman/builderthread.py
+++ b/tools/buildman/builderthread.py
@@ -90,12 +90,12 @@
         thread_num: Our thread number (0-n-1), used to decide on a
                 temporary directory
     """
-    def __init__(self, builder, thread_num, incremental, per_board_out_dir):
+    def __init__(self, builder, thread_num, mrproper, per_board_out_dir):
         """Set up a new builder thread"""
         threading.Thread.__init__(self)
         self.builder = builder
         self.thread_num = thread_num
-        self.incremental = incremental
+        self.mrproper = mrproper
         self.per_board_out_dir = per_board_out_dir
 
     def Make(self, commit, brd, stage, cwd, *args, **kwargs):
@@ -243,7 +243,7 @@
                 # If we need to reconfigure, do that now
                 if do_config:
                     config_out = ''
-                    if not self.incremental:
+                    if self.mrproper:
                         result = self.Make(commit, brd, 'mrproper', cwd,
                                 'mrproper', *args, env=env)
                         config_out += result.combined
diff --git a/tools/buildman/cmdline.py b/tools/buildman/cmdline.py
index 17ea015..1377b9d 100644
--- a/tools/buildman/cmdline.py
+++ b/tools/buildman/cmdline.py
@@ -55,8 +55,9 @@
     parser.add_option('-i', '--in-tree', dest='in_tree',
           action='store_true', default=False,
           help='Build in the source tree instead of a separate directory')
+    # -I will be removed after April 2021
     parser.add_option('-I', '--incremental', action='store_true',
-          default=False, help='Do not run make mrproper (when reconfiguring)')
+          default=False, help='Deprecated, does nothing. See -m')
     parser.add_option('-j', '--jobs', dest='jobs', type='int',
           default=None, help='Number of jobs to run at once (passed to make)')
     parser.add_option('-k', '--keep-outputs', action='store_true',
@@ -69,6 +70,8 @@
           default=False, help='Show a list of boards next to each error/warning')
     parser.add_option('--list-tool-chains', action='store_true', default=False,
           help='List available tool chains (use -v to see probing detail)')
+    parser.add_option('-m', '--mrproper', action='store_true',
+          default=False, help="Run 'make mrproper before reconfiguring")
     parser.add_option('-n', '--dry-run', action='store_true', dest='dry_run',
           default=False, help="Do a dry run (describe actions, but do nothing)")
     parser.add_option('-N', '--no-subdirs', action='store_true', dest='no_subdirs',
@@ -111,6 +114,12 @@
     parser.add_option('-x', '--exclude', dest='exclude',
           type='string', action='append',
           help='Specify a list of boards to exclude, separated by comma')
+    parser.add_option('-y', '--filter-dtb-warnings', action='store_true',
+          default=False,
+          help='Filter out device-tree-compiler warnings from output')
+    parser.add_option('-Y', '--filter-migration-warnings', action='store_true',
+          default=False,
+          help='Filter out migration warnings from output')
 
     parser.usage += """ [list of target/arch/cpu/board/vendor/soc to build]
 
diff --git a/tools/buildman/control.py b/tools/buildman/control.py
index 5ddc598..30c030f 100644
--- a/tools/buildman/control.py
+++ b/tools/buildman/control.py
@@ -172,6 +172,10 @@
         print()
         return 0
 
+    if options.incremental:
+        print(col.Color(col.RED,
+                        'Warning: -I has been removed. See documentation'))
+
     # Work out what subset of the boards we are building
     if not boards:
         if not os.path.exists(options.output_dir):
@@ -309,7 +313,7 @@
             show_unknown=options.show_unknown, step=options.step,
             no_subdirs=options.no_subdirs, full_path=options.full_path,
             verbose_build=options.verbose_build,
-            incremental=options.incremental,
+            mrproper=options.mrproper,
             per_board_out_dir=options.per_board_out_dir,
             config_only=options.config_only,
             squash_config_y=not options.preserve_config_y,
@@ -341,23 +345,23 @@
             commits = None
 
         Print(GetActionSummary(options.summary, commits, board_selected,
-                                options))
+                               options))
 
         # We can't show function sizes without board details at present
         if options.show_bloat:
             options.show_detail = True
-        builder.SetDisplayOptions(options.show_errors, options.show_sizes,
-                                  options.show_detail, options.show_bloat,
-                                  options.list_error_boards,
-                                  options.show_config,
-                                  options.show_environment)
+        builder.SetDisplayOptions(
+            options.show_errors, options.show_sizes, options.show_detail,
+            options.show_bloat, options.list_error_boards, options.show_config,
+            options.show_environment, options.filter_dtb_warnings,
+            options.filter_migration_warnings)
         if options.summary:
             builder.ShowSummary(commits, board_selected)
         else:
             fail, warned = builder.BuildBoards(commits, board_selected,
                                 options.keep_outputs, options.verbose)
             if fail:
-                return 128
+                return 100
             elif warned and not options.ignore_warnings:
-                return 129
+                return 101
     return 0
diff --git a/tools/buildman/func_test.py b/tools/buildman/func_test.py
index 2a256a9..1fbc6f6 100644
--- a/tools/buildman/func_test.py
+++ b/tools/buildman/func_test.py
@@ -454,7 +454,7 @@
         # Only sandbox should succeed, the others don't have toolchains
         self.assertEqual(self._builder.fail,
                          self._total_builds - self._commits)
-        self.assertEqual(ret_code, 128)
+        self.assertEqual(ret_code, 100)
 
         for commit in range(self._commits):
             for board in self._boards.GetList():
@@ -476,15 +476,15 @@
         self._RunControl('-b', TEST_BRANCH, '-c2', '-o', self._output_dir)
         self.assertEqual(self._builder.count, 2 * len(boards))
         self.assertEqual(self._builder.fail, 0)
-        # Each board has a mrproper, config, and then one make per commit
-        self.assertEqual(self._make_calls, len(boards) * (2 + 2))
+        # Each board has a config, and then one make per commit
+        self.assertEqual(self._make_calls, len(boards) * (1 + 2))
 
     def testIncremental(self):
         """Test building a branch twice - the second time should do nothing"""
         self._RunControl('-b', TEST_BRANCH, '-o', self._output_dir)
 
         # Each board has a mrproper, config, and then one make per commit
-        self.assertEqual(self._make_calls, len(boards) * (self._commits + 2))
+        self.assertEqual(self._make_calls, len(boards) * (self._commits + 1))
         self._make_calls = 0
         self._RunControl('-b', TEST_BRANCH, '-o', self._output_dir, clean_dir=False)
         self.assertEqual(self._make_calls, 0)
@@ -496,14 +496,26 @@
         self._RunControl('-b', TEST_BRANCH, '-o', self._output_dir)
         self._make_calls = 0
         self._RunControl('-b', TEST_BRANCH, '-f', '-o', self._output_dir, clean_dir=False)
-        # Each board has a mrproper, config, and then one make per commit
-        self.assertEqual(self._make_calls, len(boards) * (self._commits + 2))
+        # Each board has a config and one make per commit
+        self.assertEqual(self._make_calls, len(boards) * (self._commits + 1))
 
     def testForceReconfigure(self):
         """The -f flag should force a rebuild"""
         self._RunControl('-b', TEST_BRANCH, '-C', '-o', self._output_dir)
-        # Each commit has a mrproper, config and make
-        self.assertEqual(self._make_calls, len(boards) * self._commits * 3)
+        # Each commit has a config and make
+        self.assertEqual(self._make_calls, len(boards) * self._commits * 2)
+
+    def testForceReconfigure(self):
+        """The -f flag should force a rebuild"""
+        self._RunControl('-b', TEST_BRANCH, '-C', '-o', self._output_dir)
+        # Each commit has a config and make
+        self.assertEqual(self._make_calls, len(boards) * self._commits * 2)
+
+    def testMrproper(self):
+        """The -f flag should force a rebuild"""
+        self._RunControl('-b', TEST_BRANCH, '-m', '-o', self._output_dir)
+        # Each board has a mkproper, config and then one make per commit
+        self.assertEqual(self._make_calls, len(boards) * (self._commits + 2))
 
     def testErrors(self):
         """Test handling of build errors"""
@@ -525,7 +537,7 @@
         self._RunControl('-b', TEST_BRANCH, '-o', self._output_dir, '-F', clean_dir=False)
         self.assertEqual(self._builder.count, self._total_builds)
         self.assertEqual(self._builder.fail, 0)
-        self.assertEqual(self._make_calls, 3)
+        self.assertEqual(self._make_calls, 2)
 
     def testBranchWithSlash(self):
         """Test building a branch with a '/' in the name"""
diff --git a/tools/buildman/test.py b/tools/buildman/test.py
index 2aaedf4..d32b226 100644
--- a/tools/buildman/test.py
+++ b/tools/buildman/test.py
@@ -36,6 +36,14 @@
 x86: i386 x86_64
 '''
 
+migration = '''===================== WARNING ======================
+This board does not use CONFIG_DM. CONFIG_DM will be
+compulsory starting with the v2020.01 release.
+Failure to update may result in board removal.
+See doc/driver-model/migration.rst for more info.
+====================================================
+'''
+
 errors = [
     '''main.c: In function 'main_loop':
 main.c:260:6: warning: unused variable 'joe' [-Wunused-variable]
@@ -79,13 +87,14 @@
 
 # hash, subject, return code, list of errors/warnings
 commits = [
-    ['1234', 'upstream/master, ok', 0, []],
+    ['1234', 'upstream/master, migration warning', 0, []],
     ['5678', 'Second commit, a warning', 0, errors[0:1]],
     ['9012', 'Third commit, error', 1, errors[0:2]],
     ['3456', 'Fourth commit, warning', 0, [errors[0], errors[2]]],
     ['7890', 'Fifth commit, link errors', 1, [errors[0], errors[3]]],
     ['abcd', 'Sixth commit, fixes all errors', 0, []],
-    ['ef01', 'Seventh commit, check directory suppression', 1, [errors[4]]],
+    ['ef01', 'Seventh commit, fix migration, check directory suppression', 1,
+     [errors[4]]],
 ]
 
 boards = [
@@ -118,6 +127,8 @@
             comm.subject = commit_info[1]
             comm.return_code = commit_info[2]
             comm.error_list = commit_info[3]
+            if sequence < 6:
+                 comm.error_list += [migration]
             comm.sequence = sequence
             sequence += 1
             self.commits.append(comm)
@@ -143,9 +154,14 @@
         terminal.SetPrintTestMode()
         self._col = terminal.Color()
 
-    def Make(self, commit, brd, stage, *args, **kwargs):
-        global base_dir
+        self.base_dir = tempfile.mkdtemp()
+        if not os.path.isdir(self.base_dir):
+            os.mkdir(self.base_dir)
 
+    def tearDown(self):
+        shutil.rmtree(self.base_dir)
+
+    def Make(self, commit, brd, stage, *args, **kwargs):
         result = command.CommandResult()
         boardnum = int(brd.target[-1])
         result.return_code = 0
@@ -156,7 +172,9 @@
                 boardnum == 4 and commit.sequence == 6):
             result.return_code = commit.return_code
             result.stderr = (''.join(commit.error_list)
-                % {'basedir' : base_dir + '/.bm-work/00/'})
+                % {'basedir' : self.base_dir + '/.bm-work/00/'})
+        elif commit.sequence < 6:
+            result.stderr = migration
 
         result.combined = result.stdout + result.stderr
         return result
@@ -173,17 +191,19 @@
             expect += col.Color(expected_colour, ' %s' % board)
         self.assertEqual(text, expect)
 
-    def testOutput(self):
-        """Test basic builder operation and output
+    def _SetupTest(self, echo_lines=False, **kwdisplay_args):
+        """Set up the test by running a build and summary
 
-        This does a line-by-line verification of the summary output.
-        """
-        global base_dir
+        Args:
+            echo_lines: True to echo lines to the terminal to aid test
+                development
+            kwdisplay_args: Dict of arguemnts to pass to
+                Builder.SetDisplayOptions()
 
-        base_dir = tempfile.mkdtemp()
-        if not os.path.isdir(base_dir):
-            os.mkdir(base_dir)
-        build = builder.Builder(self.toolchains, base_dir, None, 1, 2,
+        Returns:
+            Iterator containing the output lines, each a PrintLine() object
+        """
+        build = builder.Builder(self.toolchains, self.base_dir, None, 1, 2,
                                 checkout=False, show_unknown=False)
         build.do_make = self.Make
         board_selected = self.boards.GetSelectedDict()
@@ -198,124 +218,238 @@
             if line.text.strip():
                 count += 1
 
-        # We should get two starting messages, then an update for every commit
-        # built.
-        self.assertEqual(count, len(commits) * len(boards) + 2)
-        build.SetDisplayOptions(show_errors=True);
+        # We should get two starting messages, an update for every commit built
+        # and a summary message
+        self.assertEqual(count, len(commits) * len(boards) + 3)
+        build.SetDisplayOptions(**kwdisplay_args);
         build.ShowSummary(self.commits, board_selected)
-        #terminal.EchoPrintTestLines()
-        lines = terminal.GetPrintTestLines()
+        if echo_lines:
+            terminal.EchoPrintTestLines()
+        return iter(terminal.GetPrintTestLines())
 
-        # Upstream commit: no errors
-        self.assertEqual(lines[0].text, '01: %s' % commits[0][1])
+    def _CheckOutput(self, lines, list_error_boards=False,
+                     filter_dtb_warnings=False,
+                     filter_migration_warnings=False):
+        """Check for expected output from the build summary
 
-        # Second commit: all archs should fail with warnings
-        self.assertEqual(lines[1].text, '02: %s' % commits[1][1])
+        Args:
+            lines: Iterator containing the lines returned from the summary
+            list_error_boards: Adjust the check for output produced with the
+               --list-error-boards flag
+            filter_dtb_warnings: Adjust the check for output produced with the
+               --filter-dtb-warnings flag
+        """
+        def add_line_prefix(prefix, boards, error_str, colour):
+            """Add a prefix to each line of a string
+
+            The training \n in error_str is removed before processing
+
+            Args:
+                prefix: String prefix to add
+                error_str: Error string containing the lines
+                colour: Expected colour for the line. Note that the board list,
+                    if present, always appears in magenta
+
+            Returns:
+                New string where each line has the prefix added
+            """
+            lines = error_str.strip().splitlines()
+            new_lines = []
+            for line in lines:
+                if boards:
+                    expect = self._col.Color(colour, prefix + '(')
+                    expect += self._col.Color(self._col.MAGENTA, boards,
+                                              bright=False)
+                    expect += self._col.Color(colour, ') %s' % line)
+                else:
+                    expect = self._col.Color(colour, prefix + line)
+                new_lines.append(expect)
+            return '\n'.join(new_lines)
 
         col = terminal.Color()
-        self.assertSummary(lines[2].text, 'arm', 'w+', ['board1'],
-                           outcome=OUTCOME_WARN)
-        self.assertSummary(lines[3].text, 'powerpc', 'w+', ['board2', 'board3'],
-                           outcome=OUTCOME_WARN)
-        self.assertSummary(lines[4].text, 'sandbox', 'w+', ['board4'],
-                           outcome=OUTCOME_WARN)
+        boards01234 = ('board0 board1 board2 board3 board4'
+                       if list_error_boards else '')
+        boards1234 = 'board1 board2 board3 board4' if list_error_boards else ''
+        boards234 = 'board2 board3 board4' if list_error_boards else ''
+        boards34 = 'board3 board4' if list_error_boards else ''
+        boards4 = 'board4' if list_error_boards else ''
+
+        # Upstream commit: migration warnings only
+        self.assertEqual(next(lines).text, '01: %s' % commits[0][1])
+
+        if not filter_migration_warnings:
+            self.assertSummary(next(lines).text, 'arm', 'w+',
+                               ['board0', 'board1'], outcome=OUTCOME_WARN)
+            self.assertSummary(next(lines).text, 'powerpc', 'w+',
+                               ['board2', 'board3'], outcome=OUTCOME_WARN)
+            self.assertSummary(next(lines).text, 'sandbox', 'w+', ['board4'],
+                               outcome=OUTCOME_WARN)
+
+            self.assertEqual(next(lines).text,
+                add_line_prefix('+', boards01234, migration, col.RED))
+
+        # Second commit: all archs should fail with warnings
+        self.assertEqual(next(lines).text, '02: %s' % commits[1][1])
+
+        if filter_migration_warnings:
+            self.assertSummary(next(lines).text, 'arm', 'w+',
+                               ['board1'], outcome=OUTCOME_WARN)
+            self.assertSummary(next(lines).text, 'powerpc', 'w+',
+                               ['board2', 'board3'], outcome=OUTCOME_WARN)
+            self.assertSummary(next(lines).text, 'sandbox', 'w+', ['board4'],
+                               outcome=OUTCOME_WARN)
 
         # Second commit: The warnings should be listed
-        self.assertEqual(lines[5].text, 'w+%s' %
-                errors[0].rstrip().replace('\n', '\nw+'))
-        self.assertEqual(lines[5].colour, col.MAGENTA)
+        self.assertEqual(next(lines).text,
+            add_line_prefix('w+', boards1234, errors[0], col.YELLOW))
 
         # Third commit: Still fails
-        self.assertEqual(lines[6].text, '03: %s' % commits[2][1])
-        self.assertSummary(lines[7].text, 'arm', '', ['board1'],
-                           outcome=OUTCOME_OK)
-        self.assertSummary(lines[8].text, 'powerpc', '+', ['board2', 'board3'])
-        self.assertSummary(lines[9].text, 'sandbox', '+', ['board4'])
+        self.assertEqual(next(lines).text, '03: %s' % commits[2][1])
+        if filter_migration_warnings:
+            self.assertSummary(next(lines).text, 'arm', '',
+                               ['board1'], outcome=OUTCOME_OK)
+        self.assertSummary(next(lines).text, 'powerpc', '+',
+                           ['board2', 'board3'])
+        self.assertSummary(next(lines).text, 'sandbox', '+', ['board4'])
 
         # Expect a compiler error
-        self.assertEqual(lines[10].text, '+%s' %
-                errors[1].rstrip().replace('\n', '\n+'))
+        self.assertEqual(next(lines).text,
+                         add_line_prefix('+', boards234, errors[1], col.RED))
 
         # Fourth commit: Compile errors are fixed, just have warning for board3
-        self.assertEqual(lines[11].text, '04: %s' % commits[3][1])
-        expect = '%10s: ' % 'powerpc'
-        expect += ' ' + col.Color(col.GREEN, '')
-        expect += '  '
-        expect += col.Color(col.GREEN, ' %s' % 'board2')
-        expect += ' ' + col.Color(col.YELLOW, 'w+')
-        expect += '  '
-        expect += col.Color(col.YELLOW, ' %s' % 'board3')
-        self.assertEqual(lines[12].text, expect)
-        self.assertSummary(lines[13].text, 'sandbox', 'w+', ['board4'],
-                           outcome=OUTCOME_WARN)
+        self.assertEqual(next(lines).text, '04: %s' % commits[3][1])
+        if filter_migration_warnings:
+            expect = '%10s: ' % 'powerpc'
+            expect += ' ' + col.Color(col.GREEN, '')
+            expect += '  '
+            expect += col.Color(col.GREEN, ' %s' % 'board2')
+            expect += ' ' + col.Color(col.YELLOW, 'w+')
+            expect += '  '
+            expect += col.Color(col.YELLOW, ' %s' % 'board3')
+            self.assertEqual(next(lines).text, expect)
+        else:
+            self.assertSummary(next(lines).text, 'powerpc', 'w+',
+                               ['board2', 'board3'], outcome=OUTCOME_WARN)
+        self.assertSummary(next(lines).text, 'sandbox', 'w+', ['board4'],
+                               outcome=OUTCOME_WARN)
 
         # Compile error fixed
-        self.assertEqual(lines[14].text, '-%s' %
-                errors[1].rstrip().replace('\n', '\n-'))
-        self.assertEqual(lines[14].colour, col.GREEN)
+        self.assertEqual(next(lines).text,
+                         add_line_prefix('-', boards234, errors[1], col.GREEN))
 
-        self.assertEqual(lines[15].text, 'w+%s' %
-                errors[2].rstrip().replace('\n', '\nw+'))
-        self.assertEqual(lines[15].colour, col.MAGENTA)
+        if not filter_dtb_warnings:
+            self.assertEqual(
+                next(lines).text,
+                add_line_prefix('w+', boards34, errors[2], col.YELLOW))
 
         # Fifth commit
-        self.assertEqual(lines[16].text, '05: %s' % commits[4][1])
-        self.assertSummary(lines[17].text, 'powerpc', '', ['board3'],
-                           outcome=OUTCOME_OK)
-        self.assertSummary(lines[18].text, 'sandbox', '+', ['board4'])
+        self.assertEqual(next(lines).text, '05: %s' % commits[4][1])
+        if filter_migration_warnings:
+            self.assertSummary(next(lines).text, 'powerpc', '', ['board3'],
+                               outcome=OUTCOME_OK)
+        self.assertSummary(next(lines).text, 'sandbox', '+', ['board4'])
 
         # The second line of errors[3] is a duplicate, so buildman will drop it
         expect = errors[3].rstrip().split('\n')
         expect = [expect[0]] + expect[2:]
-        self.assertEqual(lines[19].text, '+%s' %
-                '\n'.join(expect).replace('\n', '\n+'))
+        expect = '\n'.join(expect)
+        self.assertEqual(next(lines).text,
+                         add_line_prefix('+', boards4, expect, col.RED))
 
-        self.assertEqual(lines[20].text, 'w-%s' %
-                errors[2].rstrip().replace('\n', '\nw-'))
+        if not filter_dtb_warnings:
+            self.assertEqual(
+                next(lines).text,
+                add_line_prefix('w-', boards34, errors[2], col.CYAN))
 
         # Sixth commit
-        self.assertEqual(lines[21].text, '06: %s' % commits[5][1])
-        self.assertSummary(lines[22].text, 'sandbox', '', ['board4'],
-                           outcome=OUTCOME_OK)
+        self.assertEqual(next(lines).text, '06: %s' % commits[5][1])
+        if filter_migration_warnings:
+            self.assertSummary(next(lines).text, 'sandbox', '', ['board4'],
+                               outcome=OUTCOME_OK)
+        else:
+            self.assertSummary(next(lines).text, 'sandbox', 'w+', ['board4'],
+                               outcome=OUTCOME_WARN)
 
         # The second line of errors[3] is a duplicate, so buildman will drop it
         expect = errors[3].rstrip().split('\n')
         expect = [expect[0]] + expect[2:]
-        self.assertEqual(lines[23].text, '-%s' %
-                '\n'.join(expect).replace('\n', '\n-'))
-
-        self.assertEqual(lines[24].text, 'w-%s' %
-                errors[0].rstrip().replace('\n', '\nw-'))
+        expect = '\n'.join(expect)
+        self.assertEqual(next(lines).text,
+                         add_line_prefix('-', boards4, expect, col.GREEN))
+        self.assertEqual(next(lines).text,
+                         add_line_prefix('w-', boards4, errors[0], col.CYAN))
 
         # Seventh commit
-        self.assertEqual(lines[25].text, '07: %s' % commits[6][1])
-        self.assertSummary(lines[26].text, 'sandbox', '+', ['board4'])
+        self.assertEqual(next(lines).text, '07: %s' % commits[6][1])
+        if filter_migration_warnings:
+            self.assertSummary(next(lines).text, 'sandbox', '+', ['board4'])
+        else:
+            self.assertSummary(next(lines).text, 'arm', '', ['board0', 'board1'],
+                               outcome=OUTCOME_OK)
+            self.assertSummary(next(lines).text, 'powerpc', '',
+                               ['board2', 'board3'], outcome=OUTCOME_OK)
+            self.assertSummary(next(lines).text, 'sandbox', '+', ['board4'])
 
         # Pick out the correct error lines
         expect_str = errors[4].rstrip().replace('%(basedir)s', '').split('\n')
         expect = expect_str[3:8] + [expect_str[-1]]
-        self.assertEqual(lines[27].text, '+%s' %
-                '\n'.join(expect).replace('\n', '\n+'))
+        expect = '\n'.join(expect)
+        if not filter_migration_warnings:
+            self.assertEqual(
+                next(lines).text,
+                add_line_prefix('-', boards01234, migration, col.GREEN))
+
+        self.assertEqual(next(lines).text,
+                         add_line_prefix('+', boards4, expect, col.RED))
 
         # Now the warnings lines
         expect = [expect_str[0]] + expect_str[10:12] + [expect_str[9]]
-        self.assertEqual(lines[28].text, 'w+%s' %
-                '\n'.join(expect).replace('\n', '\nw+'))
+        expect = '\n'.join(expect)
+        self.assertEqual(next(lines).text,
+                         add_line_prefix('w+', boards4, expect, col.YELLOW))
+
+    def testOutput(self):
+        """Test basic builder operation and output
+
+        This does a line-by-line verification of the summary output.
+        """
+        lines = self._SetupTest(show_errors=True)
+        self._CheckOutput(lines, list_error_boards=False,
+                          filter_dtb_warnings=False)
+
+    def testErrorBoards(self):
+        """Test output with --list-error-boards
 
-        self.assertEqual(len(lines), 29)
-        shutil.rmtree(base_dir)
+        This does a line-by-line verification of the summary output.
+        """
+        lines = self._SetupTest(show_errors=True, list_error_boards=True)
+        self._CheckOutput(lines, list_error_boards=True)
+
+    def testFilterDtb(self):
+        """Test output with --filter-dtb-warnings
+
+        This does a line-by-line verification of the summary output.
+        """
+        lines = self._SetupTest(show_errors=True, filter_dtb_warnings=True)
+        self._CheckOutput(lines, filter_dtb_warnings=True)
+
+    def testFilterMigration(self):
+        """Test output with --filter-migration-warnings
+
+        This does a line-by-line verification of the summary output.
+        """
+        lines = self._SetupTest(show_errors=True,
+                                filter_migration_warnings=True)
+        self._CheckOutput(lines, filter_migration_warnings=True)
 
     def _testGit(self):
         """Test basic builder operation by building a branch"""
-        base_dir = tempfile.mkdtemp()
-        if not os.path.isdir(base_dir):
-            os.mkdir(base_dir)
         options = Options()
         options.git = os.getcwd()
         options.summary = False
         options.jobs = None
         options.dry_run = False
-        #options.git = os.path.join(base_dir, 'repo')
+        #options.git = os.path.join(self.base_dir, 'repo')
         options.branch = 'test-buildman'
         options.force_build = False
         options.list_tool_chains = False
@@ -328,7 +462,6 @@
         options.keep_outputs = False
         args = ['tegra20']
         control.DoBuildman(options, args)
-        shutil.rmtree(base_dir)
 
     def testBoardSingle(self):
         """Test single board selection"""
diff --git a/tools/patman/patman.py b/tools/patman/patman.py
index cf53e53..7f4ac9a 100755
--- a/tools/patman/patman.py
+++ b/tools/patman/patman.py
@@ -93,7 +93,7 @@
         suite = unittest.TestLoader().loadTestsFromTestCase(module)
         suite.run(result)
 
-    for module in ['gitutil', 'settings']:
+    for module in ['gitutil', 'settings', 'terminal']:
         suite = doctest.DocTestSuite(module)
         suite.run(result)
 
diff --git a/tools/patman/terminal.py b/tools/patman/terminal.py
index 7a3b658..5c9e3ee 100644
--- a/tools/patman/terminal.py
+++ b/tools/patman/terminal.py
@@ -10,6 +10,8 @@
 from __future__ import print_function
 
 import os
+import re
+import shutil
 import sys
 
 # Selection of when we want our output to be colored
@@ -19,6 +21,13 @@
 print_test_mode = False
 print_test_list = []
 
+# The length of the last line printed without a newline
+last_print_len = None
+
+# credit:
+# stackoverflow.com/questions/14693701/how-can-i-remove-the-ansi-escape-sequences-from-a-string-in-python
+ansi_escape = re.compile(r'\x1b(?:[@-Z\\-_]|\[[0-?]*[ -/]*[@-~])')
+
 class PrintLine:
     """A line of text output
 
@@ -36,7 +45,86 @@
         return 'newline=%s, colour=%s, text=%s' % (self.newline, self.colour,
                 self.text)
 
+def CalcAsciiLen(text):
+    """Calculate the length of a string, ignoring any ANSI sequences
+
+    When displayed on a terminal, ANSI sequences don't take any space, so we
+    need to ignore them when calculating the length of a string.
+
+    Args:
+        text: Text to check
+
+    Returns:
+        Length of text, after skipping ANSI sequences
+
+    >>> col = Color(COLOR_ALWAYS)
+    >>> text = col.Color(Color.RED, 'abc')
+    >>> len(text)
+    14
+    >>> CalcAsciiLen(text)
+    3
+    >>>
+    >>> text += 'def'
+    >>> CalcAsciiLen(text)
+    6
+    >>> text += col.Color(Color.RED, 'abc')
+    >>> CalcAsciiLen(text)
+    9
+    """
+    result = ansi_escape.sub('', text)
+    return len(result)
+
+def TrimAsciiLen(text, size):
+    """Trim a string containing ANSI sequences to the given ASCII length
+
+    The string is trimmed with ANSI sequences being ignored for the length
+    calculation.
+
-def Print(text='', newline=True, colour=None):
+    >>> col = Color(COLOR_ALWAYS)
+    >>> text = col.Color(Color.RED, 'abc')
+    >>> len(text)
+    14
+    >>> CalcAsciiLen(TrimAsciiLen(text, 4))
+    3
+    >>> CalcAsciiLen(TrimAsciiLen(text, 2))
+    2
+    >>> text += 'def'
+    >>> CalcAsciiLen(TrimAsciiLen(text, 4))
+    4
+    >>> text += col.Color(Color.RED, 'ghi')
+    >>> CalcAsciiLen(TrimAsciiLen(text, 7))
+    7
+    """
+    if CalcAsciiLen(text) < size:
+        return text
+    pos = 0
+    out = ''
+    left = size
+
+    # Work through each ANSI sequence in turn
+    for m in ansi_escape.finditer(text):
+        # Find the text before the sequence and add it to our string, making
+        # sure it doesn't overflow
+        before = text[pos:m.start()]
+        toadd = before[:left]
+        out += toadd
+
+        # Figure out how much non-ANSI space we have left
+        left -= len(toadd)
+
+        # Add the ANSI sequence and move to the position immediately after it
+        out += m.group()
+        pos = m.start() + len(m.group())
+
+    # Deal with text after the last ANSI sequence
+    after = text[pos:]
+    toadd = after[:left]
+    out += toadd
+
+    return out
+
+
+def Print(text='', newline=True, colour=None, limit_to_line=False):
     """Handle a line of output to the terminal.
 
     In test mode this is recorded in a list. Otherwise it is output to the
@@ -47,17 +135,31 @@
         newline: True to add a new line at the end of the text
         colour: Colour to use for the text
     """
+    global last_print_len
+
     if print_test_mode:
         print_test_list.append(PrintLine(text, newline, colour))
     else:
         if colour:
             col = Color()
             text = col.Color(colour, text)
-        print(text, end='')
         if newline:
-            print()
+            print(text)
+            last_print_len = None
         else:
-            sys.stdout.flush()
+            if limit_to_line:
+                cols = shutil.get_terminal_size().columns
+                text = TrimAsciiLen(text, cols)
+            print(text, end='', flush=True)
+            last_print_len = CalcAsciiLen(text)
+
+def PrintClear():
+    """Clear a previously line that was printed with no newline"""
+    global last_print_len
+
+    if last_print_len:
+        print('\r%s\r' % (' '* last_print_len), end='', flush=True)
+        last_print_len = None
 
 def SetPrintTestMode():
     """Go into test mode, where all printing is recorded"""