I'm currently trying to make changes to xmalloc/xrealloc/xfree. The
problem is, lots of code calls free() directly instead of xfree(). I am
wondering whether there is any reason that parts of ruby (or extensions to
ruby) might want to keep using free() instead of xfree() ?

I would like that xfree() be used only on memory allocated with xmalloc(),
and free() only on memory allocated with malloc(). That would help me
alot.

matju