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+/*
+ * (C) Copyright 2001
+ * Dave Ellis, SIXNET, dge@sixnetio.com
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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
+ */
+
+Using autoboot configuration options
+====================================
+
+The basic autoboot configuration options are documented in the main
+U-Boot README. See it for details. They are:
+
+  bootdelay
+  bootcmd
+  CONFIG_BOOTDELAY
+  CONFIG_BOOTCOMMAND
+
+Some additional options that make autoboot safer in a production
+product are documented here.
+
+Why use them?
+-------------
+
+The basic autoboot feature allows a system to automatically boot to
+the real application (such as Linux) without a user having to enter
+any commands. If any key is pressed before the boot delay time
+expires, U-Boot stops the autoboot process, gives a U-Boot prompt
+and waits forever for a command. That's a good thing if you pressed a
+key because you wanted to get the prompt.
+
+It's not so good if the key press was a stray character on the
+console serial port, say because a user who knows nothing about
+U-Boot pressed a key before the system had time to boot. It's even
+worse on an embedded product that doesn't have a console during
+normal use. The modem plugged into that console port sends a
+character at the wrong time and the system hangs, with no clue as to
+why it isn't working.
+
+You might want the system to autoboot to recover after an external
+configuration program stops autoboot. If the configuration program
+dies or loses its connection (modems can disconnect at the worst
+time) U-Boot will patiently wait forever for it to finish.
+
+These additional configuration options can help provide a system that
+boots when it should, but still allows access to U-Boot.
+
+What they do
+------------
+
+  CONFIG_BOOT_RETRY_TIME
+  CONFIG_BOOT_RETRY_MIN
+
+  bootretry environment variable
+
+        These options determine what happens after autoboot is
+        stopped and U-Boot is waiting for commands.
+
+        CONFIG_BOOT_RETRY_TIME must be defined to enable the boot
+        retry feature. If the environment variable 'bootretry' is
+        found then its value is used, otherwise the retry timeout is
+        CONFIG_BOOT_RETRY_TIME. CONFIG_BOOT_RETRY_MIN is optional and
+        defaults to CONFIG_BOOT_RETRY_TIME. All times are in seconds.
+
+        If the retry timeout is negative, the U-Boot command prompt
+        never times out. Otherwise it is forced to be at least
+        CONFIG_BOOT_RETRY_MIN seconds. If no valid U-Boot command is
+        entered before the specified time the boot delay sequence is
+        restarted. Each command that U-Boot executes restarts the
+        timeout.
+
+        If CONFIG_BOOT_RETRY_TIME < 0 the feature is there, but
+        doesn't do anything unless the environment variable
+        'bootretry' is >= 0.
+
+  CONFIG_AUTOBOOT_KEYED
+  CONFIG_AUTOBOOT_PROMPT
+  CONFIG_AUTOBOOT_DELAY_STR
+  CONFIG_AUTOBOOT_STOP_STR
+  CONFIG_AUTOBOOT_DELAY_STR2
+  CONFIG_AUTOBOOT_STOP_STR2
+
+  bootdelaykey	environment variable
+  bootstopkey	environment variable
+  bootdelaykey2	environment variable
+  bootstopkey2	environment variable
+
+        These options give more control over stopping autoboot. When
+        they are used a specific character or string is required to
+        stop or delay autoboot.
+
+	Define CONFIG_AUTOBOOT_KEYED (no value required) to enable
+	this group of options.  CONFIG_AUTOBOOT_DELAY_STR,
+	CONFIG_AUTOBOOT_STOP_STR or both should be specified (or
+	specified by the corresponding environment variable),
+	otherwise there is no way to stop autoboot.
+
+        CONFIG_AUTOBOOT_PROMPT is displayed before the boot delay
+        selected by CONFIG_BOOTDELAY starts. If it is not defined
+        there is no output indicating that autoboot is in progress.
+        If "%d" is included, it is replaced by the number of seconds
+        remaining before autoboot will start, but it does not count
+        down the seconds. "autoboot in %d seconds\n" is a reasonable
+        prompt.
+
+        If CONFIG_AUTOBOOT_DELAY_STR or bootdelaykey is specified and
+        this string is received from console input before autoboot
+        starts booting, U-Boot gives a command prompt. The U-Boot
+        prompt will time out if CONFIG_BOOT_RETRY_TIME is used,
+        otherwise it never times out.
+
+        If CONFIG_AUTOBOOT_STOP_STR or bootstopkey is specified and
+        this string is received from console input before autoboot
+        starts booting, U-Boot gives a command prompt. The U-Boot
+        prompt never times out, even if CONFIG_BOOT_RETRY_TIME is
+        used.
+
+        The string recognition is not very sophisticated. If a
+        partial match is detected, the first non-matching character
+        is checked to see if starts a new match. There is no check
+        for a shorter partial match, so it's best if the first
+        character of a key string does not appear in the rest of the
+        string.
+
+        Using the CONFIG_AUTOBOOT_DELAY_STR2 /  bootdelaykey2  and/or
+        CONFIG_AUTOBOOT_STOP_STR2   /   bootstopkey  #defines  and/or
+        environment variables you can  specify  a  second,  alternate
+        string (which allows you to haw two "password" strings).
+
+  CONFIG_ZERO_BOOTDELAY_CHECK
+
+        If this option is defined, you can stop the autoboot process
+        by hitting a key even in that case when "bootdelay" has been
+        set to 0. You can set "bootdelay" to a negative value to
+        prevent the check for console input.
+
+  CONFIG_RESET_TO_RETRY
+
+        (Only effective when CONFIG_BOOT_RETRY_TIME is also set)
+        After the countdown timed out, the board will be reset to restart
+        again.
+