Clarify when CoreDumpDirectory can be moot based on OS configuration, and

mention SIGQUIT/3 not being processed by the signal handler.

SIGQUIT may unfortunately be a go-to signal for java users.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@759957 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/docs/manual/mod/mpm_common.xml b/docs/manual/mod/mpm_common.xml
index 8fe038c7e8c95aa5cf1f22e84a9530bbf59819f3..c717dd274b281fa255f55159a5981a7c042a1c09 100644 (file)
--- a/docs/manual/mod/mpm_common.xml
+++ b/docs/manual/mod/mpm_common.xml
@@ -129,13 +129,17 @@ switch before dumping core</description>
 
 <usage>
     <p>This controls the directory to which Apache attempts to
-    switch before dumping core. The default is in the
-    <directive module="core">ServerRoot</directive> directory, however
-    since this should not be writable by the user the server runs
-    as, core dumps won't normally get written. If you want a core
-    dump for debugging, you can use this directive to place it in a
-    different location.</p>
-
+    switch before dumping core. If your operating system is configured to
+    create core files in the crashing processes working directory, 
+    <directive>CoreDumpDirectory</directive> is necessary to change working
+    directory from the default <directive module="core">ServerRoot</directive> 
+    directory, which should not be writable by the user the server runs as.</p>
+
+    <p>If you want a core dump for debugging, you can use this directive to 
+    place it in a different location. This directive has no effect if your
+    operating system is not configured to write core files to the crashing 
+    processes working directory.</p>
+    
     <note><title>Core Dumps on Linux</title>
       <p>If Apache starts as root and switches to another user, the
       Linux kernel <em>disables</em> core dumps even if the directory is
@@ -143,6 +147,17 @@ switch before dumping core</description>
       on Linux 2.4 and beyond, but only if you explicitly configure a <directive
       >CoreDumpDirectory</directive>.</p>
     </note>
+
+    <note><title>Specific signals</title>
+      <p><directive>CoreDumpDirectory</directive> processing only occurs for 
+      a select set of fatal signals: SIGFPE, SIGILL, SIGABORT, 
+      SIGSEGV, and SIGBUS.</p>
+      <p>On some operating systems, SIGQUIT also results in a core dump but
+      does not go through <directive>CoreDumpDirectory</directive> or
+      <directive>EnableExceptionHook</directive> processing, so the core
+      location is dictated entirely by the operating system.</p>
+    </note>
+
 </usage>
 </directivesynopsis>