Index: head/share/mk/src.opts.mk
===================================================================
--- head/share/mk/src.opts.mk
+++ head/share/mk/src.opts.mk
@@ -41,7 +41,7 @@
 # that haven't been converted over.
 #
 
-# These options are used by src the builds
+# These options are used by the src builds
 
 __DEFAULT_YES_OPTIONS = \
     ACCT \
@@ -96,7 +96,6 @@
     FTP \
     GAMES \
     GCOV \
-    GDB \
     GNU \
     GNU_DIFF \
     GNU_GREP \
@@ -263,6 +262,14 @@
 .if ${__T} == "arm" || ${__T} == "armeb"
 BROKEN_OPTIONS+=LLDB
 .endif
+# GDB in base is generally less functional than GDB in ports.  Ports GDB
+# does not yet contain kernel support for arm, and sparc64 kernel support
+# has not been tested.
+.if ${__T:Marm*} != "" || ${__T} == "sparc64"
+__DEFAULT_YES_OPTIONS+=GDB
+.else
+__DEFAULT_NO_OPTIONS+=GDB
+.endif
 # Only doing soft float API stuff on armv6
 .if ${__T} != "armv6"
 BROKEN_OPTIONS+=LIBSOFT