- disable default monitor when HMP is not available
- hide 'readline' from -mon help text
- error out on mux chardev monitor when no HMP
- skip HMP monitor terminal for gdb, return E01 for 'qRcmd' remote
  commands

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 chardev/char.c   | 7 +++++++
 gdbstub/system.c | 8 ++++++++
 system/vl.c      | 4 ++++
 qemu-options.hx  | 6 +++++-
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/chardev/char.c b/chardev/char.c
index ca8b37ed8d7..5f2b9fbc4bf 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -805,6 +805,7 @@ static Chardev *qemu_chr_new_from_name(const char *label, const char *filename,
 
     if (qemu_opt_get_bool(opts, "mux", 0)) {
         assert(permit_mux_mon);
+#ifdef CONFIG_HMP
         monitor_init_hmp(chr, true, &err);
         if (err) {
             error_report_err(err);
@@ -812,6 +813,12 @@ static Chardev *qemu_chr_new_from_name(const char *label, const char *filename,
             chr = NULL;
             goto out;
         }
+#else
+        error_report("HMP monitor is disabled");
+        object_unparent(OBJECT(chr));
+        chr = NULL;
+        goto out;
+#endif
     }
 
 out:
diff --git a/gdbstub/system.c b/gdbstub/system.c
index e86c5870abc..0c282c9c491 100644
--- a/gdbstub/system.c
+++ b/gdbstub/system.c
@@ -385,10 +385,14 @@ bool gdbserver_start(const char *device, Error **errp)
 
         qemu_add_vm_change_state_handler(gdb_vm_state_change, NULL);
 
+#ifdef CONFIG_HMP
         /* Initialize a monitor terminal for gdb */
         mon_chr = qemu_chardev_new(NULL, TYPE_CHARDEV_GDB,
                                    NULL, NULL, &error_abort);
         monitor_init_hmp(mon_chr, false, &error_abort);
+#else
+        mon_chr = NULL;
+#endif
     } else {
         qemu_chr_fe_deinit(&gdbserver_system_state.chr, true);
         mon_chr = gdbserver_system_state.mon_chr;
@@ -529,10 +533,14 @@ void gdb_handle_query_rcmd(GArray *params, void *ctx)
     len = len / 2;
     gdb_hextomem(gdbserver_state.mem_buf, gdb_get_cmd_param(params, 0)->data, len);
     g_byte_array_append(gdbserver_state.mem_buf, &zero, 1);
+#ifdef CONFIG_HMP
     qemu_chr_be_write(gdbserver_system_state.mon_chr,
                       gdbserver_state.mem_buf->data,
                       gdbserver_state.mem_buf->len);
     gdb_put_packet("OK");
+#else
+    gdb_put_packet("E01");
+#endif
 }
 
 /*
diff --git a/system/vl.c b/system/vl.c
index 4797700abd5..f9fa00de07b 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -199,7 +199,11 @@ static int has_defaults = 1;
 static int default_audio = 1;
 static int default_serial = 1;
 static int default_parallel = 1;
+#ifdef CONFIG_HMP
 static int default_monitor = 1;
+#else
+static int default_monitor; /* false */
+#endif
 static int default_floppy = 1;
 static int default_cdrom = 1;
 static bool auto_create_sdcard = true;
diff --git a/qemu-options.hx b/qemu-options.hx
index 4c1b32713e0..d788467b83f 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4941,7 +4941,11 @@ SRST
 ERST
 
 DEF("mon", HAS_ARG, QEMU_OPTION_mon, \
-    "-mon [chardev=]name[,mode=readline|control][,pretty=on|off]\n", QEMU_ARCH_ALL)
+    "-mon [chardev=]name[,mode="
+#ifdef CONFIG_HMP
+    "readline|"
+#endif
+    "control][,pretty=on|off]\n", QEMU_ARCH_ALL)
 SRST
 ``-mon [chardev=]name[,mode=readline|control][,pretty=on|off]``
     Set up a monitor connected to the chardev ``name``.

-- 
2.54.0