u-boot bootcount functionality

[AB22]

I have made the following modifications to the u-boot configuration (Yocto Scarthgap/i.MX8M Plus):

CONFIG_BOOTCOUNT=y
CONFIG_BOOTCOUNT_LIMIT=y
CONFIG_BOOTCOUNT_BOOTLIMIT=3

Every time I printenv bootcount at the u-boot prompt, the value is 1. I would like for the bootcount functionality to indicate when to fallback to a working partition during dual-copy update (SWUpdate) in the event the boot process repeatedly fails. What conditions cause the bootcount to increment? I can corrupt files and cause a stall at the u-boot prompt but nothing is providing a mechanism to initiate fallback.

[Manuel_Salas · Accepted solution]

Hello @AB22 

I hope you are doing very well.

You can see the bootcount_env.c file under uboot-imx/drivers/bootcount.

// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2013
 * Heiko Schocher, DENX Software Engineering, hs@denx.de.
 */

#include <common.h>
#include <env.h>

void bootcount_store(ulong a)
{
	int upgrade_available = env_get_ulong("upgrade_available", 10, 0);

	if (upgrade_available) {
		env_set_ulong("bootcount", a);
		env_save();
	}
}

ulong bootcount_load(void)
{
	int upgrade_available = env_get_ulong("upgrade_available", 10, 0);
	ulong val = 0;

	if (upgrade_available)
		val = env_get_ulong("bootcount", 10, 0);

	return val;
}

You need to set the environment variable called upgrade_available on your U-boot.

u-boot=> setenv upgrade_available 1

After reset:

u-boot=> printenv bootcount
bootcount=2

I hope this can helps to you.

Best regards,

Salas.

[AB22]

Thank you for pointing me to that file. It is quite helpful.

[xacov]

It should not be a question. 

https://github.com/nxp-imx/uboot-imx/blob/lf-6.1.55-2.2.0/drivers/bootcount/Kconfig

config BOOTCOUNT_ENV

bool "Boot counter in environment"

help

  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 Application must set the "upgrade_available"

  and "bootcount" variables to 0, if the system booted successfully.

[AB22]

That is quite helpful. I misunderstood the usage of upgrade_available. Thank you.