Hello!

How to determine if I have good version of cross compiler and toolchain?

I have: git://git.openwrt.org/15.05/openwrt.git
and:
BusyBox v1.23.2 (2015-07-25 15:09:46 CEST) built-in shell (ash)

  _______                     ________        __
|       |.-----.-----.-----.|  |  |  |.----.|  |_
|   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
|_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
-----------------------------------------------------
CHAOS CALMER (15.05, r46767)
-----------------------------------------------------
  * 1 1/2 oz Gin            Shake with a glassful
  * 1/4 oz Triple Sec       of broken ice and pour
  * 3/4 oz Lime Juice       unstrained into a goblet.
  * 1 1/2 oz Orange Juice
  * 1 tsp. Grenadine Syrup
-----------------------------------------------------

you have got a lot of reading to do , you are essentially asking how to build a engine while stating you have a socket and a hammer to do the job !!

There are tutorials all over the net on cross compiling a simple helloworld program .. I would suggest you start there

I did started, but of course don't understand it. Obviously this is the reason why I am asking this question. How difficult it is to see if this is the correct version for someone (like you) experienced?!

again to the point I made above, what your asking does not make any sense.. what you provided in your post is irrelevant to cross-compiling.

have a look at this, follow it step by step and if you get stuck on something post what has got you stuck and any relevant error messages and we will gladly push you along .. but to try and explain the entire process to you in a thread when you obviously have a minimal understanding of the process does no one any good. trail and error and ask well thought out and coherent questions .. that's how I learned the ropes

https://manoftoday.wordpress.com/2007/1 … r-openwrt/

On which system/distribution are you trying to cross-compile?

I cross-compiled OpenWrt on both Ubuntu Trusty 14.04 and Debian Jessie 8 and didn't find any problems or incompatibilities there. I just followed the wiki instructions on setting up the build environment (i.e. installing some required packages) and was good to go.