[Qemu-devel] [PATCH 22/22] machine: introduce -machine-def option to define a machine via config

[Anthony Liguori <aliguori@us.ibm.com>]

Since we have MachineCore and can represent a machine entirely via default
options, we can introduce a new option that let's us dynamically register a
machine based on those options.

For instance, we could add the following to target-x86_64.conf:

[machine-def]
 name = "pc-0.11"
 desc = "Standard PC"
 acpi = "on"
 pci = "on"
 cpu = "qemu64"
 max_cpus = "255"
 virtio-blk-pci.vectors = "0"
 virtio-serial-pci.max_nr_ports = "1"
 virtio-serial-pci.vectors = "0"
 ide-drive.ver = "0.11"
 scsi-disk.ver = "0.11"
 PCI.rombar = "0"

What's really exciting, is that a user can then define their own machines
that better suite their desires:

[kvmpc]
 name = "kvmpc"
 accel = "kvm|tcg"
 ram_size = "512M"
 max_cpus = "64"
 sockets = "16"
 default_drive = "virtio"

I'd eventually like to move all PC compatibility machines to the default
config but for now, I wanted to keep this simple.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/qemu-config.c b/qemu-config.c
index a0cb34f..9b5415d 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -345,6 +345,15 @@ QemuOptsList qemu_machine_opts = {
     },
 };        
 
+QemuOptsList qemu_machine_def_opts = {
+    .name = "machine-def",
+    .implied_opt_name = "name",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_machine_def_opts.head),
+    .desc = {
+        { /* end of list */ }
+    },
+};
+
 static QemuOptsList *vm_config_groups[] = {
     &qemu_drive_opts,
     &qemu_chardev_opts,
@@ -356,6 +365,7 @@ static QemuOptsList *vm_config_groups[] = {
     &qemu_mon_opts,
     &qemu_cpudef_opts,
     &qemu_machine_opts,
+    &qemu_machine_def_opts,
     NULL,
 };
 
diff --git a/qemu-config.h b/qemu-config.h
index 6f52188..1b7324c 100644
--- a/qemu-config.h
+++ b/qemu-config.h
@@ -15,6 +15,7 @@ extern QemuOptsList qemu_global_opts;
 extern QemuOptsList qemu_mon_opts;
 extern QemuOptsList qemu_cpudef_opts;
 extern QemuOptsList qemu_machine_opts;
+extern QemuOptsList qemu_machine_def_opts;
 
 QemuOptsList *qemu_find_opts(const char *group);
 int qemu_set_option(const char *str);
diff --git a/qemu-options.hx b/qemu-options.hx
index 32fd32a..2bafe22 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -43,6 +43,14 @@ STEXI
 Select the emulated @var{machine}
 ETEXI
 
+DEF("machine-def", HAS_ARG, QEMU_OPTION_machine_def,
+    "-machine-def name[,opt=val...] define a new machine\n", QEMU_ARCH_ALL)
+STEXI
+@item -machine-def @var{name}[,@var{opt}=@var{val}...]
+@findex -machine-def
+Define a new machine
+ETEXI
+
 DEF("cpu", HAS_ARG, QEMU_OPTION_cpu,
     "-cpu cpu        select CPU (-cpu ? for list)\n", QEMU_ARCH_ALL)
 STEXI
diff --git a/vl.c b/vl.c
index 150dd41..7797187 100644
--- a/vl.c
+++ b/vl.c
@@ -1683,6 +1683,59 @@ void machine_set_default(const char *name)
     default_machine = name;
 }
 
+typedef struct MachineDefineHelper
+{
+    QemuOptValue *defaults;
+    int length;
+    int capacity;
+} MachineDefineHelper;
+
+static void helper_grow(MachineDefineHelper *helper)
+{
+    if ((helper->capacity - helper->length) < 2) {
+        helper->capacity += 100;
+        helper->defaults = qemu_realloc(helper->defaults,
+                                        helper->capacity * sizeof(QemuOptValue));
+    }
+}
+
+static int machine_define_prop(const char *name, const char *value, void *opaque)
+{
+    MachineDefineHelper *helper = opaque;
+    QemuOptValue *v;
+
+    if (strcmp(name, "core") == 0) {
+        return 0;
+    }
+
+    helper_grow(helper);
+    v = &helper->defaults[helper->length++];
+    v->name = qemu_strdup(name);
+    v->value = qemu_strdup(value);
+
+    return 0;
+}
+
+static int machine_define(QemuOpts *opts, void *opaque)
+{
+    MachineDefineHelper *helper;
+    const char *core;
+
+    core = qemu_opt_get(opts, "core");
+    if (!core) {
+        fprintf(stderr, "machine-def: No core specified\n");
+        return -1;
+    }
+
+    helper = qemu_mallocz(sizeof(*helper));
+    qemu_opt_foreach(opts, machine_define_prop, helper, 1);
+    helper->defaults[helper->length].name = NULL;
+    machine_create_from_core(core, helper->defaults);
+    qemu_free(helper);
+
+    return 0;
+}
+
 static Machine *find_machine(const char *name)
 {
     Machine *m;
@@ -2812,6 +2865,7 @@ int main(int argc, char **argv, char **envp)
         }
     }
     cpudef_init();
+    qemu_opts_foreach(&qemu_machine_def_opts, machine_define, NULL, 1);
 
     /* second pass of option parsing */
     optind = 1;
@@ -2853,6 +2907,14 @@ int main(int argc, char **argv, char **envp)
                     exit(1);
                 }
                 break;
+            case QEMU_OPTION_machine_def:
+                opts = qemu_opts_parse(&qemu_machine_def_opts, optarg, 1);
+                if (!opts) {
+                    exit(1);
+                }
+
+                machine_define(opts, NULL);
+                break;
             case QEMU_OPTION_cpu:
                 /* hw initialization will check this */
                 if (*optarg == '?') {
-- 
1.7.0.4