[porters-handbook]: Clarify prefixes in patch file names

Patches must start with `patch-` in order to be applied automatically.
Conditional patches must not start with `patch-`.

PR: 24903
Reported by:	pauamma@gundo.com

Approved by: 0mp (mentor)
Differential Revision: https://reviews.freebsd.org/D28268

1 files changed, 4 insertions, 0 deletions

diff --git a/documentation/content/en/books/porters-handbook/slow-porting/_index.adoc b/documentation/content/en/books/porters-handbook/slow-porting/_index.adoc
index f40a105bac..4146408768 100644
--- a/documentation/content/en/books/porters-handbook/slow-porting/_index.adoc
+++ b/documentation/content/en/books/porters-handbook/slow-porting/_index.adoc
@@ -132,6 +132,7 @@ Manual patch creation is usually not necessary. Automatic patch generation as de
 ====
 
 Patches are saved into files named [.filename]#patch-*# where * indicates the pathname of the file that is patched, such as [.filename]#patch-Imakefile# or [.filename]#patch-src-config.h#.
+Patches with file names which do not start with [.filename]#patch-# will not be applied automatically.
 
 After the file has been modified, man:diff[1] is used to record the differences between the original and the modified version. `-u` causes man:diff[1] to produce "unified" diffs, the preferred form.
 
@@ -208,6 +209,9 @@ DOS2UNIX_WRKSRC=	${WRKDIR}
 === Patching Conditionally
 
 Some ports need patches that are only applied for specific FreeBSD 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`.
+Conditional patch file names usually start with [.filename]#extra-# although this is not necessary.
+However, their file names _must not_ start with [.filename]#patch-#.
+If they do, they are applied unconditionally by the framework which is undesired for conditional patches.
 
 [[slow-patch-extra-ex1]]
 .Applying a Patch for a Specific FreeBSD Version