[gclist] What wrong with the GC in xemacs

[Nick Barnes]

> But don't generational (and incremental, for that matter) GCs require
> a write barrier?

Mostly, yes.

> If so, then modifying Emacs would be a big pain.  There is code all
> over Emacs that looks like this:
> 
> 	CDR(foo) = ...
> 
> Every such assignment would have to be found and modified -- the very
> definition of "tedious" and "error-prone".

Write barriers do not necessarily involve modifying any mutator
code. They can work with non-cooperative mutators by using OS
memory-protection facilities.

Emacs could certainly be changed to do this, on platforms which
supported it.

Nick Barnes, speaking for himself