[PULL,1/5] hw/loongarch: Add compat machine for 9.1

Commit Message

gaosong May 16, 2024, 9:11 a.m. UTC

From: Bibo Mao <[e-mail]>

Since migration test case requires compat machine type support,
compat machine is added for qemu 9.1 here.

Signed-off-by: Bibo Mao <[e-mail]>
Reviewed-by: Song Gao <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Song Gao <[e-mail]>
---
 hw/loongarch/virt.c | 61 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 48 insertions(+), 13 deletions(-)

Comments

Peter Maydell May 16, 2024, 9:27 a.m. UTC | #1

On Thu, 16 May 2024 at 10:12, Song Gao <[e-mail]> wrote:
>
> From: Bibo Mao <[e-mail]>
>
> Since migration test case requires compat machine type support,
> compat machine is added for qemu 9.1 here.

This is not a good justification for adding versioned machine types.
Adding versioned machine types is putting a massive maintenance
burden on yourself from now onward:
 * every release needs a new machine type adding
 * every change to the board model or to any devices it uses needs
   to be assessed for cross-version compatibility issues, and
   if necessary extra properties must be added so old versions
   of the board model keep the legacy backwards-compatible behaviour
 * migration compatibility must be maintained

You really do not want to do this until you decide that your
architecture and machine type are at a level where this is a
support guarantee you want to provide to users. "It lets us
run a test case" is not a good reason to do it, and I strongly
recommend you do not add versioned machine types just for that.

thanks
-- PMM

Patch

diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index f0640d2d80..f24ff5fcf4 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -1231,18 +1231,53 @@  static void virt_class_init(ObjectClass *oc, void *data)
 #endif
 }
 
-static const TypeInfo virt_machine_types[] = {
-    {
-        .name           = TYPE_LOONGARCH_VIRT_MACHINE,
-        .parent         = TYPE_MACHINE,
-        .instance_size  = sizeof(LoongArchVirtMachineState),
-        .class_init     = virt_class_init,
-        .instance_init  = virt_initfn,
-        .interfaces = (InterfaceInfo[]) {
-         { TYPE_HOTPLUG_HANDLER },
-         { }
-        },
-    }
+#define DEFINE_VIRT_MACHINE_LATEST(major, minor, latest) \
+    static void virt_##major##_##minor##_class_init(ObjectClass *oc, \
+                                                    void *data) \
+    { \
+        MachineClass *mc = MACHINE_CLASS(oc); \
+        virt_machine_##major##_##minor##_options(mc); \
+        mc->desc = "QEMU " # major "." # minor " LoongArch Virtual Machine"; \
+        if (latest) { \
+            mc->alias = "virt"; \
+        } \
+    } \
+    static const TypeInfo machvirt_##major##_##minor##_info = { \
+        .name = MACHINE_TYPE_NAME("virt-" # major "." # minor), \
+        .parent = TYPE_LOONGARCH_VIRT_MACHINE, \
+        .class_init = virt_##major##_##minor##_class_init, \
+    }; \
+    static void machvirt_machine_##major##_##minor##_init(void) \
+    { \
+        type_register_static(&machvirt_##major##_##minor##_info); \
+    } \
+    type_init(machvirt_machine_##major##_##minor##_init);
+
+#define DEFINE_VIRT_MACHINE_AS_LATEST(major, minor) \
+    DEFINE_VIRT_MACHINE_LATEST(major, minor, true)
+#define DEFINE_VIRT_MACHINE(major, minor) \
+    DEFINE_VIRT_MACHINE_LATEST(major, minor, false)
+
+static const TypeInfo virt_machine_info = {
+    .name           = TYPE_LOONGARCH_VIRT_MACHINE,
+    .parent         = TYPE_MACHINE,
+    .abstract       = true,
+    .instance_size  = sizeof(LoongArchVirtMachineState),
+    .class_init     = virt_class_init,
+    .instance_init  = virt_initfn,
+    .interfaces = (InterfaceInfo[]) {
+    { TYPE_HOTPLUG_HANDLER },
+    { }
+    },
 };
 
-DEFINE_TYPES(virt_machine_types)
+static void machvirt_machine_init(void)
+{
+    type_register_static(&virt_machine_info);
+}
+type_init(machvirt_machine_init);
+
+static void virt_machine_9_1_options(MachineClass *mc)
+{
+}
+DEFINE_VIRT_MACHINE_AS_LATEST(9, 1)