wic: Add plugin for single partition disk

The wic plugin creates a disk image containig one ext2/3/4 partition.
No additional boot partition is required. Syslinux is installed into
the image. The target device is a legacy BIOS PC.

Purpose of this plugin:
Other avaliable plugins create a fat partition for /boot and an ext
partition for rootfs. Current linux-yocto kernel packages are not
compatible with this disk layout. The boot partition is not mounted
by default, hence the kernel is installed into rootfs and not into
boot partition. A kernel update ends up in a bricked device. The old
kernel which is still in boot likely does not even boot with updated
kernel modules from /. Even if the boot partition is mounted during
the kernel update the update will fail. The kernel package installs
a symbolic link which is not supported by the fat partition.
Creating just one ext partition for boot and rootfs solves all issues
related to package based kernel updates on the device.

The plugin depends on syslinux-nomtools a user space installer for
syslinux on ext filesystems.
Thanks to Robert Yang who implemented syslinux-nomtools and supported
the implementation of this plugin.

Signed-off-by: Adrian Freihofer <adrian.freihofer@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 240 insertions, 0 deletions

diff --git a/scripts/lib/wic/plugins/source/rootfs_pcbios_ext.py b/scripts/lib/wic/plugins/source/rootfs_pcbios_ext.py
new file mode 100644
index 0000000000..ebf95ae097
--- /dev/null
+++ b/scripts/lib/wic/plugins/source/rootfs_pcbios_ext.py
@@ -0,0 +1,182 @@
+# ex:ts=4:sw=4:sts=4:et
+# -*- tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#
+# This program is free software; you can distribute 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 mo 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.
+#
+# AUTHOR
+# Adrian Freihofer <adrian.freihofer (at] neratec.com>
+#
+
+import os
+from wic import kickstart
+from wic import msger
+from wic.utils import syslinux
+from wic.utils import runner
+from wic.utils.oe import misc
+from wic.utils.errors import ImageError
+from wic.pluginbase import SourcePlugin
+
+
+# pylint: disable=no-init
+class RootfsPlugin(SourcePlugin):
+    """
+    Create root partition and install syslinux bootloader
+
+    This plugin creates a disk image containing a bootable root partition with
+    syslinux installed. The filesystem is ext2/3/4, no extra boot partition is
+    required.
+
+    Example kickstart file:
+    part / --source rootfs-pcbios-ext --ondisk sda --fstype=ext4 --label rootfs --align 1024
+    bootloader --source rootfs-pcbios-ext --timeout=0 --append="rootwait rootfstype=ext4"
+
+    The first line generates a root file system including a syslinux.cfg file
+    The "--source rootfs-pcbios-ext" in the second line triggers the installation
+    of ldlinux.sys into the image.
+    """
+
+    name = 'rootfs-pcbios-ext'
+
+    @staticmethod
+    def _get_rootfs_dir(rootfs_dir):
+        """
+        Find rootfs pseudo dir
+
+        If rootfs_dir is a directory consider it as rootfs directory.
+        Otherwise ask bitbake about the IMAGE_ROOTFS directory.
+        """
+        if os.path.isdir(rootfs_dir):
+            return rootfs_dir
+
+        bitbake_env_lines = misc.find_bitbake_env_lines(rootfs_dir)
+        if not bitbake_env_lines:
+            msger.error("Couldn't get bitbake environment, exiting.")
+
+        image_rootfs_dir = misc.find_artifact(bitbake_env_lines, "IMAGE_ROOTFS")
+        if not os.path.isdir(image_rootfs_dir):
+            msg = "No valid artifact IMAGE_ROOTFS from image named"
+            msg += " %s has been found at %s, exiting.\n" % \
+                (rootfs_dir, image_rootfs_dir)
+            msger.error(msg)
+
+        return image_rootfs_dir
+
+    # pylint: disable=unused-argument
+    @classmethod
+    def do_configure_partition(cls, part, source_params, image_creator,
+                               image_creator_workdir, oe_builddir, bootimg_dir,
+                               kernel_dir, native_sysroot):
+        """
+        Creates syslinux config in rootfs directory
+
+        Called before do_prepare_partition()
+        """
+        rootdev = image_creator._get_boot_config()[0]
+        options = image_creator.ks.handler.bootloader.appendLine
+
+        syslinux_conf = ""
+        syslinux_conf += "PROMPT 0\n"
+
+        timeout = kickstart.get_timeout(image_creator.ks)
+        if not timeout:
+            timeout = 0
+        syslinux_conf += "TIMEOUT " + str(timeout) + "\n"
+        syslinux_conf += "ALLOWOPTIONS 1\n"
+
+        # Derive SERIAL... line from from kernel boot parameters
+        syslinux_conf += syslinux.serial_console_form_kargs(options) + "\n"
+
+        syslinux_conf += "DEFAULT linux\n"
+        syslinux_conf += "LABEL linux\n"
+        syslinux_conf += "  KERNEL /boot/bzImage\n"
+
+        if image_creator._ptable_format == 'msdos':
+            rootstr = rootdev
+        else:
+            raise ImageError("Unsupported partition table format found")
+
+        syslinux_conf += "  APPEND label=boot root=%s %s\n" % (rootstr, options)
+
+        syslinux_cfg = os.path.join(image_creator.rootfs_dir['ROOTFS_DIR'], "boot", "syslinux.cfg")
+        msger.debug("Writing syslinux config %s" % syslinux_cfg)
+        with open(syslinux_cfg, "w") as cfg:
+            cfg.write(syslinux_conf)
+
+    @classmethod
+    def do_prepare_partition(cls, part, source_params, image_creator,
+                             image_creator_workdir, oe_builddir, bootimg_dir,
+                             kernel_dir, krootfs_dir, native_sysroot):
+        """
+        Creates partition out of rootfs directory
+
+        Prepare content for a rootfs partition i.e. create a partition
+        and fill it from a /rootfs dir.
+        Install syslinux bootloader into root partition image file
+        """
+        def is_exe(exepath):
+            """Verify exepath is an executable file"""
+            return os.path.isfile(exepath) and os.access(exepath, os.X_OK)
+
+        # Make sure syslinux-nomtools is available in native sysroot or fail
+        native_syslinux_nomtools = os.path.join(native_sysroot, "usr/bin/syslinux-nomtools")
+        if not is_exe(native_syslinux_nomtools):
+            msger.info("building syslinux-native...")
+            misc.exec_cmd("bitbake syslinux-native")
+        if not is_exe(native_syslinux_nomtools):
+            msger.error("Couldn't find syslinux-nomtools (%s), exiting\n" %
+                        native_syslinux_nomtools)
+
+        if part.rootfs is None:
+            if 'ROOTFS_DIR' not in krootfs_dir:
+                msger.error("Couldn't find --rootfs-dir, exiting")
+            rootfs_dir = krootfs_dir['ROOTFS_DIR']
+        else:
+            if part.rootfs in krootfs_dir:
+                rootfs_dir = krootfs_dir[part.rootfs]
+            elif part.rootfs:
+                rootfs_dir = part.rootfs
+            else:
+                msg = "Couldn't find --rootfs-dir=%s connection"
+                msg += " or it is not a valid path, exiting"
+                msger.error(msg % part.rootfs)
+
+        real_rootfs_dir = cls._get_rootfs_dir(rootfs_dir)
+
+        part.set_rootfs(real_rootfs_dir)
+        part.prepare_rootfs(image_creator_workdir, oe_builddir, real_rootfs_dir, native_sysroot)
+
+        # install syslinux into rootfs partition
+        syslinux_cmd = "syslinux-nomtools -d /boot -i %s" % part.source_file
+        misc.exec_native_cmd(syslinux_cmd, native_sysroot)
+
+    @classmethod
+    def do_install_disk(cls, disk, disk_name, image_creator, workdir, oe_builddir,
+                        bootimg_dir, kernel_dir, native_sysroot):
+        """
+        Assemble partitions to disk image
+
+        Called after all partitions have been prepared and assembled into a
+        disk image. In this case, we install the MBR.
+        """
+        mbrfile = os.path.join(native_sysroot, "usr/share/syslinux/mbr.bin")
+        if not os.path.exists(mbrfile):
+            msger.error("Couldn't find %s. Has syslinux-native been baked?" % mbrfile)
+
+        full_path = disk['disk'].device
+        msger.debug("Installing MBR on disk %s as %s with size %s bytes" \
+                    % (disk_name, full_path, disk['min_size']))
+
+        ret_code = runner.show(['dd', 'if=%s' % mbrfile, 'of=%s' % full_path, 'conv=notrunc'])
+        if ret_code != 0:
+            raise ImageError("Unable to set MBR to %s" % full_path)
diff --git a/scripts/lib/wic/utils/syslinux.py b/scripts/lib/wic/utils/syslinux.py
new file mode 100644
index 0000000000..aace2863c1
--- /dev/null
+++ b/scripts/lib/wic/utils/syslinux.py
@@ -0,0 +1,58 @@
+# ex:ts=4:sw=4:sts=4:et
+# -*- tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; version 2 of the License
+#
+# 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., 59
+# Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+#
+# AUTHOR
+# Adrian Freihofer <adrian.freihofer (at] neratec.com>
+
+
+import re
+from wic import msger
+
+
+def serial_console_form_kargs(kernel_args):
+    """
+    Create SERIAL... line from kernel parameters
+
+    syslinux needs a line SERIAL port [baudrate [flowcontrol]]
+    in the syslinux.cfg file. The config line is generated based
+    on kernel boot parameters. The the parameters of the first
+    ttyS console are considered for syslinux config.
+    @param kernel_args kernel command line
+    @return line for syslinux config file e.g. "SERIAL 0 115200"
+    """
+    syslinux_conf = ""
+    for param in kernel_args.split():
+        param_match = re.match("console=ttyS([0-9]+),?([0-9]*)([noe]?)([0-9]?)(r?)", param)
+        if param_match:
+            syslinux_conf += "SERIAL " + param_match.group(1)
+            # baudrate
+            if param_match.group(2):
+                syslinux_conf += " " + param_match.group(2)
+            # parity
+            if param_match.group(3) and param_match.group(3) != 'n':
+                msger.warning("syslinux does not support parity for console. {} is ignored."
+                              .format(param_match.group(3)))
+            # number of bits
+            if param_match.group(4) and param_match.group(4) != '8':
+                msger.warning("syslinux supports 8 bit console configuration only. {} is ignored."
+                              .format(param_match.group(4)))
+            # flow control
+            if param_match.group(5) and param_match.group(5) != '':
+                msger.warning("syslinux console flowcontrol configuration. {} is ignored."
+                              .format(param_match.group(5)))
+            break
+
+    return syslinux_conf