SenoraGC is a relatively portable conservative GC for a slightly
cooperative environment.

The collector is intended mainly for debugging and memory tracing, but
it can also act as a reasonbaly efficient, general-purpose,
conservative collector. The standard Racket build uses SGC for
certain platforms where Boehm's GC hasn't been ported, yet (notably,
OSKit and BeOS).

This collector is not recommended as a replacement for Boehm's GC if
you can get Boehm's to work at all. SenoraGC MIGHT be useful if, for
some reason, Boehm's collector does not work for your platform.
SenoraGC MIGHT be useful as a debugging collector if you can figure
out the [undocumented] debugging utilities.

Usage:

The stack base must be manually identified with GC_set_stack_base();
no garbage collection will occur before this function is called.

All non-stack/register roots (i.e., global variables) must be
registered with GC_add_roots(). For certain platforms, this is
actually done automatically for static variables, but it can't be done
portably in general. (See AUTO_STATIC_ROOTS_IF_POSSIBLE in the flags
section.)

GC space is allocated using malloc() and free(). Alternatively, the GC
can define malloc() and free() itself if platform-specific allocation
routines are supported.