bootcount: store bootcount var in environment
If no softreset save registers are found on the hardware
"bootcount" is stored in the environment. To prevent a
saveenv on all reboots, the environment variable
"upgrade_available" is introduced. If "upgrade_available" is
0, "bootcount" is always 0 therefore no need to save the
environment on u-boot boot, if "upgrade_available" is 1 "bootcount"
is incremented in the environment and environment gets written
on u-boot start.
So the Userspace Applikation must set the "upgrade_available"
and "bootcount" variable to 0 (for example with fw_setenv),
if a boot was successfully.
Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/README b/README
index a70475f..39b3fe6 100644
--- a/README
+++ b/README
@@ -784,6 +784,22 @@
as a convenience, when switching between booting from
RAM and NFS.
+- Bootcount:
+ CONFIG_BOOTCOUNT_LIMIT
+ Implements a mechanism for detecting a repeating reboot
+ cycle, see:
+ http://www.denx.de/wiki/view/DULG/UBootBootCountLimit
+
+ CONFIG_BOOTCOUNT_ENV
+ If no softreset save registers are found on the hardware
+ "bootcount" is stored in the environment. To prevent a
+ saveenv on all reboots, the environment variable
+ "upgrade_available" is used. If "upgrade_available" is
+ 0, "bootcount" is always 0, if "upgrade_available" is
+ 1 "bootcount" is incremented in the environment.
+ So the Userspace Applikation must set the "upgrade_available"
+ and "bootcount" variable to 0, if a boot was successfully.
+
- Pre-Boot Commands:
CONFIG_PREBOOT