[OpenWrt-Devel] OpenWRT support for MPR-A1
felix at fetzig.org
Sat Oct 4 07:59:28 EDT 2014
Am 04.10.2014 um 03:43 schrieb Stefan Monnier:
> AFAICT OpenWRT comes with some support for the Hame MPR-A1 thingy
> (although its 16MB of RAM and 4MB of flash probably prevent it from
> being fully supported).
Yes, the MPR-A1 is supported. Also fully so, but it's pretty much
impossible to get LuCI to work on it with acceptable performance at just
16MB of RAM.
> The page for MPR-A2 (whose hardware and firmware seem very similar) says
> that the image can be installed via the factory web UI.
> Does someone know if that would work for the MPR-A1 as well?
Probably not. As far as I remember at least some MPR-A1 use a kind of
XOR obfuscation to "encrypt" their firmware image. We implemented a tool
to create or extract these kind of images called mkporayfw (hint: it's
in tools/firmware-utils, if you successfully completed a build already
you should find binaries for it in build_dir/host/firmware-utils/bin).
You use it like this to create a factory image for the MPR-A1:
./mkporayfw -B MPR-A1 -f <path to your MPR-A1
squashfs-sysupgrade.bin> -o <output-filename.bin>
I wonder why no one got around to implementing the automatic generation
of obfuscated images in target/linux/ramips/image/Makefile like we did
for the Poray boards.
> And if it doesn't work, would it just immediately fail, leaving the
> factory firmware untouched, or would it result in an unbootable machine
> (and if so would it be recoverable via the serial console)?
That I don't know. I never owned a MPR-A1. But what these devices have
in common is that they all use Ralink's u-boot. That means you will be
able to recover from a bad flash using the console for input and TFTP
for file transfer (unless you overwrite the bootloader in flash on
purpose or by accident, although I never had that happen to me while
heavily fiddling around with all the other RT5350 boards I have.)
My guess would be it will fail if obfuscation is active on your board's
factory firmware and the image has the incorrect checksum after
obfuscation or wasn't obfuscated at all. If the checksum is correct it
will probably flash whatever you throw at it. That means that you might
very well render your board unbootable (also in the extended sense of
board does boot but no network connection to it is possible) but not
unrecoverable. However, the images built through the OpenWrt build
system should generally boot okay.
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