[Qemu-devel] [PATCH 3/4] Add -defaults option to allow default devices to be overridden

[Anthony Liguori]

This option can be used to toggle whether each default device is enabled or
disabled.  For character devices, the default backend can also be overridden.

For devices, we'll have to take a different approach to changing the defaults
which will be covered in the next patch.

N.B. I took special care with -nographic.  Now -nographic pretty clearly acts
as a mechanism to override the default backend devices.

Signed-off-by: Anthony Liguori <address@hidden>
---
 qemu-config.c   |   45 +++++++++++++++++++++++++++++++++
 qemu-config.h   |    1 +
 qemu-options.hx |    7 +++++
 vl.c            |   75 +++++++++++++++++++++++++++++++++++++++++--------------
 4 files changed, 109 insertions(+), 19 deletions(-)

diff --git a/qemu-config.c b/qemu-config.c
index c3203c8..82ca399 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -242,6 +242,50 @@ QemuOptsList qemu_mon_opts = {
     },
 };
 
+QemuOptsList qemu_default_opts = {
+    .name = "default",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_default_opts.head),
+    .desc = {
+        {
+            .name = "serial",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "parallel",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "virtcon",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "monitor",
+            .type = QEMU_OPT_STRING,
+        },
+        {
+            .name = "vga",
+            .type = QEMU_OPT_BOOL,
+        },
+        {
+            .name = "net",
+            .type = QEMU_OPT_BOOL,
+        },
+        {
+            .name = "floppy",
+            .type = QEMU_OPT_BOOL,
+        },
+        {
+            .name = "cdrom",
+            .type = QEMU_OPT_BOOL,
+        },
+        {
+            .name = "sdcard",
+            .type = QEMU_OPT_BOOL,
+        },
+        { /* end if list */ }
+    },
+};
+
 static QemuOptsList *lists[] = {
     &qemu_drive_opts,
     &qemu_chardev_opts,
@@ -250,6 +294,7 @@ static QemuOptsList *lists[] = {
     &qemu_net_opts,
     &qemu_rtc_opts,
     &qemu_global_opts,
+    &qemu_default_opts,
     &qemu_mon_opts,
     NULL,
 };
diff --git a/qemu-config.h b/qemu-config.h
index dd89ae4..14ed67b 100644
--- a/qemu-config.h
+++ b/qemu-config.h
@@ -9,6 +9,7 @@ extern QemuOptsList qemu_net_opts;
 extern QemuOptsList qemu_rtc_opts;
 extern QemuOptsList qemu_global_opts;
 extern QemuOptsList qemu_mon_opts;
+extern QemuOptsList qemu_default_opts;
 
 int qemu_set_option(const char *str);
 int qemu_global_option(const char *str);
diff --git a/qemu-options.hx b/qemu-options.hx
index 57f453d..e81ecb5 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1919,6 +1919,13 @@ STEXI
 Don't create default devices.
 ETEXI
 
+DEF("default", HAS_ARG, QEMU_OPTION_default, \
+    "-default arg    specify default devices\n")
+STEXI
address@hidden -defaults
+Override builtin default devices
+ETEXI
+
 #ifndef _WIN32
 DEF("chroot", HAS_ARG, QEMU_OPTION_chroot, \
     "-chroot dir     chroot to dir just before starting the VM\n")
diff --git a/vl.c b/vl.c
index cf12ab0..6a3529e 100644
--- a/vl.c
+++ b/vl.c
@@ -280,6 +280,11 @@ static int default_floppy = 1;
 static int default_cdrom = 1;
 static int default_sdcard = 1;
 
+static const char *default_serial_opt = "vc:80Cx24C";
+static const char *default_parallel_opt = "vc:80Cx24C";
+static const char *default_monitor_opt = "vc:80Cx24C";
+static const char *default_virtcon_opt = "vc:80Cx24C";
+
 static struct {
     const char *driver;
     int *flag;
@@ -4658,6 +4663,32 @@ static int debugcon_parse(const char *devname)
     return 0;
 }
 
+static int default_opt_init(QemuOpts *opts, void *dummy)
+{
+    const char *opt;
+
+    if ((opt = qemu_opt_get(opts, "serial"))) {
+        default_serial_opt = opt;
+    }
+    if ((opt = qemu_opt_get(opts, "parallel"))) {
+        default_parallel_opt = opt;
+    }
+    if ((opt = qemu_opt_get(opts, "virtcon"))) {
+        default_virtcon_opt = opt;
+    }
+    if ((opt = qemu_opt_get(opts, "monitor"))) {
+        default_monitor_opt = opt;
+    }
+
+    default_vga = qemu_opt_get_bool(opts, "vga", default_vga);
+    default_net = qemu_opt_get_bool(opts, "net", default_net);
+    default_floppy = qemu_opt_get_bool(opts, "floppy", default_floppy);
+    default_cdrom = qemu_opt_get_bool(opts, "cdrom", default_cdrom);
+    default_sdcard = qemu_opt_get_bool(opts, "sdcard", default_sdcard);
+
+    return 0;
+}
+
 int main(int argc, char **argv, char **envp)
 {
     const char *gdbstub_dev = NULL;
@@ -5409,6 +5440,13 @@ int main(int argc, char **argv, char **envp)
                 default_cdrom = 0;
                 default_sdcard = 0;
                 break;
+            case QEMU_OPTION_default:
+                opts = qemu_opts_parse(&qemu_default_opts, optarg, NULL);
+                if (!opts) {
+                    fprintf(stderr, "parse error: %s\n", optarg);
+                    exit(1);
+                }
+                break;
 #ifndef _WIN32
             case QEMU_OPTION_chroot:
                 chroot_dir = optarg;
@@ -5509,6 +5547,7 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }
 
+    qemu_opts_foreach(&qemu_default_opts, default_opt_init, NULL, 0);
     qemu_opts_foreach(&qemu_device_opts, default_driver_check, NULL, 0);
     qemu_opts_foreach(&qemu_global_opts, default_driver_check, NULL, 0);
 
@@ -5535,30 +5574,28 @@ int main(int argc, char **argv, char **envp)
     }
 
     if (display_type == DT_NOGRAPHIC) {
-        if (default_parallel)
-            add_device_config(DEV_PARALLEL, "null");
+        default_parallel_opt = "null";
+
         if (default_serial && default_monitor) {
-            add_device_config(DEV_SERIAL, "mon:stdio");
+            default_serial_opt = "mon:stdio";
         } else if (default_virtcon && default_monitor) {
-            add_device_config(DEV_VIRTCON, "mon:stdio");
+            default_virtcon_opt = "mon:stdio";
         } else {
-            if (default_serial)
-                add_device_config(DEV_SERIAL, "stdio");
-            if (default_virtcon)
-                add_device_config(DEV_VIRTCON, "stdio");
-            if (default_monitor)
-                monitor_parse("stdio", "readline");
+            default_serial_opt = "stdio";
+            default_virtcon_opt = "stdio";
+            default_monitor_opt = "stdio";
         }
-    } else {
-        if (default_serial)
-            add_device_config(DEV_SERIAL, "vc:80Cx24C");
-        if (default_parallel)
-            add_device_config(DEV_PARALLEL, "vc:80Cx24C");
-        if (default_monitor)
-            monitor_parse("vc:80Cx24C", "readline");
-        if (default_virtcon)
-            add_device_config(DEV_VIRTCON, "vc:80Cx24C");
     }
+
+    if (default_serial)
+        add_device_config(DEV_SERIAL, default_serial_opt);
+    if (default_parallel)
+        add_device_config(DEV_PARALLEL, default_parallel_opt);
+    if (default_monitor)
+        monitor_parse(default_monitor_opt, "readline");
+    if (default_virtcon)
+        add_device_config(DEV_VIRTCON, default_virtcon_opt);
+
     if (default_vga)
         vga_interface_type = VGA_CIRRUS;
 
-- 
1.6.5.2