util: Add miniconfig, a script to minimize coreboot configurations

This script produces a "minimal" configuration from a full coreboot
configuration, e.g. a configuration file that only contains the differences
between the default configuration of a board and the input configuration
file.

Usage: util/kconfig/miniconfig config.big config.mini

This will read config.big and produce config.mini. If you omit config.mini,
config.big will be changed in place.

Minimal configurations are easier to read and more robust when reusing
them among different versions of coreboot as they reflect exactly the
changes made to the default configuration instead of a full snapshot
of all configuration options.

Change-Id: Ifbee49e0192c2c557b18bcc1a92fe2a5d5164a3a
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/8974
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

util/kconfig/miniconfig

@@ -0,0 +1,88 @@
+#!/bin/bash
+#
+# miniconfig - utility to minimize your coreboot config files
+#
+# Copyright 2015 Google Inc.
+#
+# 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.
+#
+
+CONFIG=$1
+NEWCONFIG=$2
+
+CONF=build/util/kconfig/conf
+KCONFIG=src/Kconfig
+DOTCONFIG=.config
+PREVCONFIG=.config.prev
+TMPCONFIG=.config.mini
+
+recreate_config()
+{
+	$CONF --olddefconfig $KCONFIG &> /dev/null
+}
+
+if [ "$CONFIG" == "" ]; then
+  printf "usage: util/miniconfig/miniconfig [path to config file] <path to new config file>\n"
+  exit 0
+fi
+
+if [ ! -r "$CONFIG" ]; then
+  printf "Can't read $CONFIG.\n"
+  exit 1
+fi
+
+if [ "$CONFIG" == .config ]; then
+  printf "Can't use .config, it's overwritten. Make a backup.\n"
+  exit 1
+fi
+
+if [ ! -x "$CONF" ]; then
+  printf "conf utility at $CONF not available.\n"
+  exit 1
+fi
+
+# Start out by creating a default config file for a mainboard
+VENDOR=$( grep ^CONFIG_VENDOR "$CONFIG" )
+BOARD=$( grep ^CONFIG_BOARD "$CONFIG" | grep -v ROMSIZE | grep -v SPECIFIC_OPTIONS )
+
+printf "$VENDOR\n$BOARD\n" > "$TMPCONFIG"
+cp "$TMPCONFIG" "$DOTCONFIG"
+recreate_config
+
+LINES=$( cat "$CONFIG" | wc -l )
+CUR=1
+
+# Now go through each line of the existing, large config file, add it to our
+# new minimal config file, and see if it makes a difference when running "make
+# olddefconfig". If it does, keep the line, otherwise discard it.
+
+cat "$CONFIG" | while read L; do
+  printf "\rProcessing $CONFIG - $CUR / $LINES (%d%%)" $(( $CUR * 100 / $LINES))
+  mv "$DOTCONFIG" "$PREVCONFIG"
+  cp "$TMPCONFIG" "$DOTCONFIG"
+  echo "$L" >> "$DOTCONFIG"
+  recreate_config
+
+  if ! diff -q "$DOTCONFIG" "$PREVCONFIG" > /dev/null; then
+    echo "$L" >> "$TMPCONFIG"
+  fi
+  CUR=$(( $CUR + 1 ))
+done
+
+echo
+
+if [ "$NEWCONFIG" != "" ]; then
+  printf "Writing new, minimized config to $NEWCONFIG\n"
+  mv "$TMPCONFIG" "$NEWCONFIG"
+else
+  printf "Overwriting $CONFIG with new, minimized config.\n"
+  mv "$TMPCONFIG" "$CONFIG"
+fi
+