read-only GC spaces

	I wonder, what it'd take to implement read-only GC spaces,
	either a read-only space for two-space GC, or arbitrary number
	of read-only spaces for Bibop?

	The implementation of read-only GC spaces would allow for mmap
	() system call to be used to memory-less map scheme48.image (or,
	possibly, even arbitrary data arrays), thus drastically reducing
	the per-process memory consumption for Scheme48 (from, I
	believe, about 5 MiB on amd64 currently, to probably less than 1
	MiB.)

	Also, it would allow for the whole Scheme48 run-time system to
	be pre-compiled into the image, thus saving both the time
	(otherwise needed to byte-compile the code) and memory space
	when loading extensions, thus making Scheme48 behavior
	comparable the the one of the languages (implementations) making
	use of shared libraries, such as C or Chicken Scheme, with
	respect to the memory consumption.

	I guess that since Bibop already supports multiple spaces, it'd
	be easier to implement read-only spaces support for it than for
	the two-space GC?  Is there any description of its internals, or
	should I start with the source code?

	Should the mmap () support be then implemented somewhere deeply
	within the VM?