Add --bootargs option to build_image.

src/platform/installer/chromeos-common.sh

 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # This contains common constants and functions for installer scripts. This must
 # evaluate properly for both /bin/bash and /bin/sh, since it's used both to
 # create the initial image at compile time and to install or upgrade a running
 # image.
 
 # Here are the GUIDs we'll be using to identify various partitions. NOTE: The
@@ skipping 443 matching lines @@
 # $1 : Kernel Partition Offset.
 # $2 : Kernel Partition Size ( in Sectors ).
 # $3 : DEVICE
 # Return file path of the generated PMBR.
 
 make_arm_mbr() {
   # Create the U-Boot script to copy the kernel into memory and boot it.
   local KERNEL_OFFSET=$(printf "0x%08x" ${1})
   local KERNEL_SECS_HEX=$(printf "0x%08x" ${2})
   local DEVICE=${3}
+  local EXTRA_BOOTARGS=${4}
 
   BOOTARGS="root=/dev/mmcblk${DEVICE}p3"
   BOOTARGS="${BOOTARGS} init=/sbin/init"
   BOOTARGS="${BOOTARGS} console=ttySAC2,115200"
   BOOTARGS="${BOOTARGS} mem=1024M"
   BOOTARGS="${BOOTARGS} rootwait"
+  BOOTARGS="${BOOTARGS} ${EXTRA_BOOTARGS}"
 
   MBR_SCRIPT="/var/tmp/mbr_script"
   echo -e "echo\necho ---- ChromeOS Boot ----\necho\n" \
           "setenv bootargs ${BOOTARGS}\n" \
           "mmc read ${DEVICE} C0008000 $KERNEL_OFFSET $KERNEL_SECS_HEX\n" \
           "bootm C0008000" > ${MBR_SCRIPT}
   MKIMAGE="/usr/bin/mkimage"
   if [ -x "$MKIMAGE" ]; then
     MBR_SCRIPT_UIMG="${MBR_SCRIPT}.uimg"
     "$MKIMAGE" -A "arm" -O linux  -T script -a 0 -e 0 -n "COS boot" \
                -d ${MBR_SCRIPT} ${MBR_SCRIPT_UIMG} >&2
   else
     echo "Error: u-boot mkimage not found or not executable." >&2
     exit 1
   fi
   echo ${MBR_SCRIPT_UIMG}
 }