I'm creating an XMPP chatbot for the Arduino Yun. However, I'm not too confident in the Python performance on such a low performance device and I'm much more comfortable with C++. Is there a C++ crosscompile environment available, and is there a port of the Bridge library to C++? Alternatively, documentation on how to interface with the ATMega using raw serial communication?
The Linux side of the Yun is just an OpenWRT installation. It has hardly been modified at all.
To cross-compile you will first need a Linux computer, or a Linux virtual machine. Then you need to download the OpenWRT source code and configure it for the Yun (I think it defaults to the right settings). Then you can build the whole OpenWRT image. One side-effect of that is it compiles and configures a full cross-compiling environment for you.
You can then use that cross-compiling environment to compile your own code.
Even if compiling C++ on the openwrt of the yun is possible with the last release of the yun-openwrt you should make a yun build-chain. That makes you compile on you computer for the processor architecture of the embedded machine on the yun.
I have never done but you can find some informations about it in those links: - https://github.com/arduino/openwrt-yun - http://fibasile.github.io/arduino-yun-custom-buildroot.html - http://fibasile.github.io/compiling-nodejs-for-arduino-yun.html - https://github.com/arduino/openwrt-yun/issues/20
For the other question.. for sure you can read/write serial directly from the openwrt. You need to disable the Bridge library (there are a lot of post around the internet. one is this one see the
Disabling the Bridge Script chapter) and manually handle the serial communication.
Hope it helps!