+;;; And there have been some changes since the fork from CMU CL:
+;;; * The OpenBSD port is new since the fork. We started with
+;;; the FreeBSD address map, which actually worked until the
+;;; Alpha port patches, for reasons which in retrospect are rather
+;;; mysterious. After the Alpha port patches were added, the
+;;; OpenBSD port suffered memory corruption problems. While
+;;; debugging those, it was discovered that src/runtime/trymap
+;;; failed for the control stack region #x40000000-#x47fff000.
+;;; After the control stack was moved upward out of this region
+;;; (stealing some bytes from dynamic space) the problems went
+;;; away.