In April 2012, I wrote an article in Software Developer's Journal Extra 02/2010(4). It was about the internals of porting the binutils and GCC to a new target, based on the case of the m68k-atari-mint cross-tools for the Atari ST.
Normally, you have to subscribe to Software Developer's Journal and pay a 1-year subscription to get the magazine.
But exceptionally, I got the permission to redistribute it for free. Enjoy!