Index: head/en_US.ISO8859-1/books/porters-handbook/slow-porting/chapter.xml
===================================================================
--- head/en_US.ISO8859-1/books/porters-handbook/slow-porting/chapter.xml
+++ head/en_US.ISO8859-1/books/porters-handbook/slow-porting/chapter.xml
@@ -450,6 +450,50 @@
USES= dos2unix
DOS2UNIX_WRKSRC= ${WRKDIR}
+
+
+ Patching Conditionally
+
+ Some ports need patches that are only applied for specific
+ &os; versions or when a particular option is enabled or
+ disabled. Conditional patches are specified by placing the
+ full paths to the patch files in
+ EXTRA_PATCHES.
+
+
+ Applying a Patch for a Specific &os; Version
+
+ .include <bsd.port.options.mk>
+
+# Patch in the iconv const qualifier before this
+.if ${OPSYS} == FreeBSD && ${OSVERSION} < 1100069
+EXTRA_PATCHES= ${PATCHDIR}/extra-patch-fbsd10
+.endif
+
+.include <bsd.port.mk>
+
+
+
+
+ Optionaly Applying a Patch
+
+ When an option
+ requires a patch, use
+ opt_EXTRA_PATCHES
+ and
+ opt_EXTRA_PATCHES_OFF
+ to make the patch conditional on the
+ opt option.
+ See for more
+ information.
+
+ OPTIONS_DEFINE= FOO BAR
+FOO_EXTRA_PATCHES= ${PATCHDIR}/extra-patch-foo
+BAR_EXTRA_PATCHES_OFF= ${PATCHDIR}/extra-patch-bar.c \
+ ${PATCHDIR}/extra-patch-bar.h
+
+
+