Firmware upgrade for Embedded Linux Device

http://www.embeddedrelated.com/usenet/embedded/show/21493-1.php



I devised the following system for an embedded linux system:

In flash I have:-

Backup Kernel
Backup Ramdisk
Operational Kernel
Operational Ramdisk
Bootloader

These images are compressed and checksummed.

When I load firmware, I buffer the image in RAM, verify the checksum, and
then copy over the operational firmware in flash. The Bootloader is never
field upgraded.

At boot time I set a flag in static RAM and count boot attempts. If a boot
fails the watchdog will reset the system. I cycle through each possible
combination of Kernel and Ramdisk [starting with the operational copies
and trying each combination 3 times if necessary].

When the system has booted, I start a little task that interrogates the
flags set by the bootloader, works out which images it booted from, compares
the checksum of the images it booted from with the images it didn't boot
from, and if they're different the image we booted from is copied over the
image we didn't boot from.

So far, I have never had a system fail to boot, despite power interruptions
during firmware upgrades and other fun things.



FROM EMBEDDED LINUX VIRTUAL CONFERENCE
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WanQiang(Quentin) YANG (10/22/2010 4:20:38 AM): Hi, what's the common way or is there common way to do firmware upgrade with embedded Linux? For our previous products without RTOS, firmware itself is able to reprogram the whole flash(ROM) with new firmware delievered via 3G modem.

Mike Anderson (10/22/2010 4:22:31 AM):@Wan: You could certainly do it that way. Boot firmware like UBoot could support that. But, I normally have a piece of firmware that I never allow the users to update so they can't brick the box. Then the O/S & filesystem are updated in flash via the boot firmware like you've done in the past

WanQiang(Quentin) YANG (10/22/2010 4:25:45 AM):Yeah, in our previous product, one piece of code, we call it bootloader, can never be upgraded, which stay same in a certain part of FLASH.
Raghavendra Reddy Desai (10/22/2010 4:28:20 AM):@ EROL :for cortex-M3 try using openICE EDS

WanQiang(Quentin) YANG (10/22/2010 4:28:40 AM):So, you reckon, I can do the same thing, get one level of boot loader before UBoot to manage the Embedded Linux upgrade for both Kernel and File System. Thanks. That'll be part of job outside of Linux Porting.

Mike Anderson (10/22/2010 4:29:25 AM):@Wan: Yes, that's what we've done many times in the past and that seems to work reliably. Good luck.