.cdepn files are used to generate the callgraph. You need to compile your program with patched gcc to create .cdepn files. Patches and patching and installing scripts are included in CodeViz download.
When you have .cdepn files, run
to generate dot definition file of full callgraph.
genfull -g cdepn -o full.graph
gengraph generates a postscript file from graph definition specified with -g. You can use it to create subgraphs specifiyng top level unctions with -f, ignored function with -i and more (for help run gengraph –man).
gengraph -k -v -f top_func -g full.graph -o full.ps
Will generate a .svg file of subgraph using fdp roadmap.
fdp -Tsvg sub.graph > sub_fdp.svg
Will generate a .png image of fullgraph using circo roadmap.
circo -Tpng full.graph > full_circo.png
Now how does it look like? Here is dot and fdp of windows manager dwm with top level function manage.