[Qemu-devel] [PATCH 1/2] Add GDB qAttached support

[Fabien Chouteau]

With this patch GDB will issue a "detach" command at the end of a
debugging session instead of a "kill". This behavior can be inverted
with the new option -gdb-not-attached.

This patch implements the requirement described in Jan Kiszka's patch:
"gdbstub: Do not kill target in system emulation mode". The patch can
therefore be reverted.

Signed-off-by: Fabien Chouteau <address@hidden>
---
 gdbstub.c              |   13 ++++++++++++-
 include/exec/gdbstub.h |    2 ++
 qemu-options.hx        |    7 +++++++
 vl.c                   |    3 +++
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/gdbstub.c b/gdbstub.c
index e414ad9..c0686a9 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -32,7 +32,6 @@
 #include "monitor/monitor.h"
 #include "char/char.h"
 #include "sysemu/sysemu.h"
-#include "exec/gdbstub.h"
 #endif
 
 #define MAX_PACKET_LENGTH 4096
@@ -41,6 +40,9 @@
 #include "qemu/sockets.h"
 #include "sysemu/kvm.h"
 #include "qemu/bitops.h"
+#include "exec/gdbstub.h"
+
+static bool gdb_attached = true;
 
 #ifndef TARGET_CPU_MEMORY_RW_DEBUG
 static inline int target_memory_rw_debug(CPUArchState *env, target_ulong addr,
@@ -2491,6 +2493,10 @@ static int gdb_handle_packet(GDBState *s, const char 
*line_buf)
             break;
         }
 #endif
+        if (strncmp(p, "Attached", 8) == 0) {
+            put_packet(s, gdb_attached ? "1" : "0");
+            break;
+        }
         /* Unrecognised 'q' command.  */
         goto unknown_command;
 
@@ -3055,3 +3061,8 @@ int gdbserver_start(const char *device)
     return 0;
 }
 #endif
+
+void gdb_set_attached(bool attached)
+{
+    gdb_attached = attached;
+}
diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index ba20afa..b2d3b13 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -50,4 +50,6 @@ int gdbserver_start(const char *port);
 /* in gdbstub-xml.c, generated by scripts/feature_to_c.sh */
 extern const char *const xml_builtin[][2];
 
+void gdb_set_attached(bool attached);
+
 #endif
diff --git a/qemu-options.hx b/qemu-options.hx
index 6f9334a..026d3eb 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2988,6 +2988,13 @@ property must be set.  These objects are placed in the
 '/objects' path.
 ETEXI
 
+DEF("gdb-not-attached", 0, QEMU_OPTION_gdb_not_attached,
+    "-gdb-not-attached\n"
+    "                Do not set Gdb remote server in attached mode.\n"
+    "                When exiting debugging session, Gdb will send a 'kill'\n"
+    "                command instead of a 'detach'.\n",
+    QEMU_ARCH_ALL)
+
 HXCOMM This is the last statement. Insert new options before this line!
 STEXI
 @end table
diff --git a/vl.c b/vl.c
index c03edf1..ccd7405 100644
--- a/vl.c
+++ b/vl.c
@@ -3815,6 +3815,9 @@ int main(int argc, char **argv, char **envp)
                     exit(1);
                 }
                 break;
+            case QEMU_OPTION_gdb_not_attached:
+                gdb_set_attached(false);
+                break;
             default:
                 os_parse_cmd_args(popt->index, optarg);
             }
-- 
1.7.9.5