I want to modify and compile ICAROS operating system iteself.
As deadwood already wrote. Icaros' foundation is based on the AROS source-code (which is freely available).
On top of that the distributor of Icaros added some of his own extensions on top of AROS by means of scripts, placing certain files/icons art atc at certain locations and modifications to the AROS default startup scripts etc. On top of that Icaros adds 3th party software, specially and painstakingly gathered/modifed and or configured by the Icaros distributor.
afaik everything in Icaros that is an addition to AROS (except for the 3th party software) is freely available on the Icaros distribution media and also afaik none of the additions that Icaros puts on top of AROS are closed source (you would have to ask the Icaros distributor if that is 100% accurate, again that is not perse true for the additional 3th party software).
You would also have to take a good look at the Icaros Desktop license in order to make sure that it is allowed for you to make modifications (not talking about distribution there).
To make it more clear: there is no Icaros source-code. Everything you see in Icaros is build on top of AROS.
I have no idea if the distributor of Icaros has some form of build system and/or if that is open source. Last time I checked most (if not all) of his efforts of putting Icaros together is a work of manual labour.
