Document a non-standard gdbremote protocol extension (kludge, really)

that I snuck in to our GDB last year.  This allows you to debug headless
machines by sharing the console port between the debugger and the system
console.  It's not 100% reliabile, but it works well.  It's optional
and disabled by default.
Submitted by:	Juniper Networks

6 files changed, 60 insertions, 4 deletions

diff --git a/sys/amd64/amd64/amd64-gdbstub.c b/sys/amd64/amd64/amd64-gdbstub.c
index e019fef..dac5f3e 100644
--- a/sys/amd64/amd64/amd64-gdbstub.c
+++ b/sys/amd64/amd64/amd64-gdbstub.c
@@ -103,6 +103,7 @@
 #include <setjmp.h>
 
 #include "sio.h"
+#include "opt_ddb.h"
 
 #if NSIO == 0
 void
@@ -250,6 +251,19 @@ putpacket (char *buffer)
   /*  $<packet info>#<checksum>. */
   do
     {
+/*
+ * This is a non-standard hack to allow use of the serial console for
+ * operation as well as debugging.  Simply turn on 'remotechat' in gdb.
+ *
+ * This extension is not part of the Cygnus protocol, is kinda gross,
+ * but gets the job done.
+ */
+#ifdef GDB_REMOTE_CHAT
+      putDebugChar ('|');
+      putDebugChar ('|');
+      putDebugChar ('|');
+      putDebugChar ('|');
+#endif
       putDebugChar ('$');
       checksum = 0;
       count = 0;
diff --git a/sys/conf/NOTES b/sys/conf/NOTES
index e4ba034..2202011 100644
--- a/sys/conf/NOTES
+++ b/sys/conf/NOTES
@@ -2,7 +2,7 @@
 # LINT -- config file for checking all the sources, tries to pull in
 #	as much of the source tree as it can.
 #
-#	$Id: LINT,v 1.341 1997/06/04 04:55:26 pst Exp $
+#	$Id: LINT,v 1.342 1997/06/04 16:25:05 pst Exp $
 #
 # NB: You probably don't want to try running a kernel built from this
 # file.  Instead, you should start from GENERIC, and add options from
@@ -256,6 +256,15 @@ options		DDB
 #
 options		DDB_UNATTENDED
 
+#
+# If using GDB remote mode to debug the kernel, there's a non-standard
+# extension to the remote protocol that can be used to use the serial
+# port as both the debugging port and the system console.  It's non-
+# standard and you're on your own if you enable it.  See also the
+# "remotechat" variables in the FreeBSD specific version of gdb.
+#
+options		GDB_REMOTE_CHAT
+
 # 
 # KTRACE enables the system-call tracing facility ktrace(2).
 #
diff --git a/sys/conf/options b/sys/conf/options
index ff394b4..62cf779 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -1,4 +1,4 @@
-#	$Id: options,v 1.29 1997/02/22 09:28:14 peter Exp $
+#	$Id: options,v 1.30 1997/05/04 15:24:13 joerg Exp $
 
 # Format:
 # Option name	filename
@@ -7,6 +7,7 @@
 BOUNCE_BUFFERS	opt_bounce.h
 DDB
 DDB_UNATTENDED	opt_ddb.h
+GDB_REMOTE_CHAT	opt_ddb.h
 DEVFS_ROOT	opt_devfs.h
 KTRACE
 QUOTA
diff --git a/sys/i386/conf/LINT b/sys/i386/conf/LINT
index e4ba034..2202011 100644
--- a/sys/i386/conf/LINT
+++ b/sys/i386/conf/LINT
@@ -2,7 +2,7 @@
 # LINT -- config file for checking all the sources, tries to pull in
 #	as much of the source tree as it can.
 #
-#	$Id: LINT,v 1.341 1997/06/04 04:55:26 pst Exp $
+#	$Id: LINT,v 1.342 1997/06/04 16:25:05 pst Exp $
 #
 # NB: You probably don't want to try running a kernel built from this
 # file.  Instead, you should start from GENERIC, and add options from
@@ -256,6 +256,15 @@ options		DDB
 #
 options		DDB_UNATTENDED
 
+#
+# If using GDB remote mode to debug the kernel, there's a non-standard
+# extension to the remote protocol that can be used to use the serial
+# port as both the debugging port and the system console.  It's non-
+# standard and you're on your own if you enable it.  See also the
+# "remotechat" variables in the FreeBSD specific version of gdb.
+#
+options		GDB_REMOTE_CHAT
+
 # 
 # KTRACE enables the system-call tracing facility ktrace(2).
 #
diff --git a/sys/i386/conf/NOTES b/sys/i386/conf/NOTES
index e4ba034..2202011 100644
--- a/sys/i386/conf/NOTES
+++ b/sys/i386/conf/NOTES
@@ -2,7 +2,7 @@
 # LINT -- config file for checking all the sources, tries to pull in
 #	as much of the source tree as it can.
 #
-#	$Id: LINT,v 1.341 1997/06/04 04:55:26 pst Exp $
+#	$Id: LINT,v 1.342 1997/06/04 16:25:05 pst Exp $
 #
 # NB: You probably don't want to try running a kernel built from this
 # file.  Instead, you should start from GENERIC, and add options from
@@ -256,6 +256,15 @@ options		DDB
 #
 options		DDB_UNATTENDED
 
+#
+# If using GDB remote mode to debug the kernel, there's a non-standard
+# extension to the remote protocol that can be used to use the serial
+# port as both the debugging port and the system console.  It's non-
+# standard and you're on your own if you enable it.  See also the
+# "remotechat" variables in the FreeBSD specific version of gdb.
+#
+options		GDB_REMOTE_CHAT
+
 # 
 # KTRACE enables the system-call tracing facility ktrace(2).
 #
diff --git a/sys/i386/i386/i386-gdbstub.c b/sys/i386/i386/i386-gdbstub.c
index e019fef..dac5f3e 100644
--- a/sys/i386/i386/i386-gdbstub.c
+++ b/sys/i386/i386/i386-gdbstub.c
@@ -103,6 +103,7 @@
 #include <setjmp.h>
 
 #include "sio.h"
+#include "opt_ddb.h"
 
 #if NSIO == 0
 void
@@ -250,6 +251,19 @@ putpacket (char *buffer)
   /*  $<packet info>#<checksum>. */
   do
     {
+/*
+ * This is a non-standard hack to allow use of the serial console for
+ * operation as well as debugging.  Simply turn on 'remotechat' in gdb.
+ *
+ * This extension is not part of the Cygnus protocol, is kinda gross,
+ * but gets the job done.
+ */
+#ifdef GDB_REMOTE_CHAT
+      putDebugChar ('|');
+      putDebugChar ('|');
+      putDebugChar ('|');
+      putDebugChar ('|');
+#endif
       putDebugChar ('$');
       checksum = 0;
       count = 0;