Created attachment 153111 [details] patch for geom_map.c, NOTES and options geom_map(4) is present in kernel source since 9.0-RELEASE but is not included in sys/conf/options and does not build for amd64 due to printf format bugs. The following patch makes it possible to use "options GEOM_MAP" in a kernel configuration file, includes GEOM_MAP to the NOTES and fixes format bugs. The patch is production-tested with amd64 platform and compile-tested with i386.
Suggected code changes are already in stable/10 (and 9.3 is EoL). It needs to update sys/conf/options and sys/conf/NOTES only.
A commit references this bug: Author: ae Date: Mon Aug 21 10:07:13 UTC 2017 New revision: 322744 URL: https://svnweb.freebsd.org/changeset/base/322744 Log: MFC r284152: Add makefile to build geom_map kld. Document some GEOM_* options in NOTES and geom(4). PR: 197766 Approved by: re (kib) Changes: _U stable/10/ stable/10/share/man/man4/geom.4 stable/10/share/man/man4/geom_map.4 stable/10/sys/conf/NOTES stable/10/sys/conf/options stable/10/sys/modules/geom/geom_map/