Getting U-boot's Version from Userspace

Does anyone know of a way to get U-boot version ins开发者_Go百科talled from userspace? There is the fw_printenv command that provides access to U-boot's environment variables, but not the version.

If U-boot is located in mtd0, you can get version info as follows:

root@SUPERWIFI:/proc# strings /dev/mtd0 | grep U-Boot    
U-Boot 1.1.4-g1c8343c8-dirty (Feb 28 2014 - 13:56:54)
U-Boot
Now running in RAM - U-Boot at: %08lx

Just an update for this. In our version of U-Boot we changed the code for main_loop() in main.c to this:

#ifdef CONFIG_VERSION_VARIABLE
    char *oldver=getenv("ver");
    if(oldver==0 ||strcmp(oldver,version_string))
    {
        setenv("ver", version_string);  /* set version variable */
        saveenv();
    }
#endif /* CONFIG_VERSION_VARIABLE */

So setenv/saveenv is only called, if needed by an update. In our firmware we added

/sbin/fw_printenv -n ver > /var/config/u-boot.ver

to make the u-boot version public available.

There's no defined way to do this. Once Linux boots, u-boot is no longer running and it's RAM is reclaimed for Linux's use. Linux doesn't even know about u-boot. Nor does it have to have been booted by u-boot.

If you really want to do this, the only way to do it is to add the u-boot version to the kernel's command line, write code to scan the u-boot image in flash for it's version, or something even nastier.

An alternative solution is to read the version directly from the u-boot binary file (can be even embedded in an image file containing other binaries as well like e.g. the first stage bootloader) with e.g. mmcblk0boot0 as partition (of device mmcblk0) the bootloader resides in:

sudo grep -a --null-data U-Boot /dev/mmcblk0boot0

Site note: Does work not only for Arch Linux but e.g. Ubuntu as well.

In my devices UBoot automatically creates a "ver" environment variable containing its version:

U-Boot > printenv
baudrate=115200
ethact=FEC ETHERNET
ethaddr=24-db-ad-00-00-08
bootdelay=3
bootcmd=bootm fc080000 - fc060000
bootargs=console=ttyCPM0,115200n8 rdinit=/sbin/init
stdin=serial
stdout=serial
stderr=serial
ver=U-Boot 2009.03-svn9684 (Mar 08 2010 - 17:08:32)

Environment size: 253/131068 bytes
U-Boot >

I don't use fw_printenv, but I would imagine that this variable gets passed along as well. Maybe you already have something similar in your system?

UPDATE (5/23/2012): I added fw_printenv to my linux image and can confirm that I do see the "ver" variable:

[root@ST600 /]# fw_printenv
baudrate=115200
ethact=FEC ETHERNET
ethaddr=24-db-ad-00-00-08
stdin=serial
stdout=serial
stderr=serial
ver=U-Boot 2009.03-svn9684 (Mar 11 2010 - 09:43:08)
bootcmd=bootm fc080000 - fc060000
bootdelay=3
bootargs=console=ttyCPM0,115200n8 rdinit=/sbin/init panic=10 mem=32m
[root@ST600 /]#

Try to read uboot version this way:

1. Find uboot partition, eg. for MTD device:

   cat /proc/mtd

2. For /dev/mtd5:

   cat /dev/mtd5 | hexdump -C -n 64

You can't rely on fw_printenv if you want to know u-boot version.

fw_printenv just looks for the printenv partition and dumps its data. So it's OK for normal variables, but it's not OK for the "ver" variable, which is dynamic, and whose value is initialized by u-boot when it boots. The value of this variable doesn't remain after u-boot exit, except if you manually save it to environment.

For example, on my board, if I print the "ver" variable from u-boot prompt:

U-Boot >      printenv ver
ver=U-Boot 2009.11-00393-g5ca9497-dirty (Nov 26 2012 - 11:08:44)

This is the real version of u-boot, coming from u-boot itself.

Now, if I boot my board and use fw_printenv:

el@board # fw_printenv | grep ver=
ver=U-Boot 2009.11-00323-gbcc6e0e (Sep 21 2012 - 11:07:19)

As you can see, it's different. Because it happens that I have a "ver" variable defined in my environment. And it doesn't match the real u-boot version.

Of course, I could go back to u-boot, use "saveenv" to update the "ver" value in the environment. Then the two values would match. But then, I should always update the environment after changing u-boot.

So, my conclusion is that using fw_printenv to get u-boot version is definitely not a good idea.

If u-boot is residing in an MTD partition then this will work:

U_BOOT_VER=$(for part in `grep u-boot-[01] /proc/mtd | cut -f 1 -d ':'`; do strings /dev/${part} | grep "^U-Boot.*("; break; done)