The oldest machine type which is still used in a still maintained distro
is a pc-0.12 based machine type in RHEL6, so everything that is older
than pc-0.12 should not be used anymore. Thus let's deprecate pc-0.10
and pc-0.11 so that we can finally remove them in a future release.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 This is based on a patch that I already sent in 2017. But back then, we
 were still in progress of discussing our deprecation policies (e.g. auto-
 matic deprecation for old machine types), and there was no clear consensus
 whether we should deprecate 0.10 - 0.11, all 0.x or even up to version 1.2.
 After some iterations and too much discussion, I've forgotten about this
 patch. Anyway, I think we agreed that at least 0.10 and 0.11 can certainly
 be removed nowadays, so let's finally get at least those two machine types
 marked as deprecated! If that works fine and we will finally have removed
 these two types in v3.2, we can resume the discussion about newer machine
 types afterwards.

 Note: I don't want to add a QMP interface for this in this patch here,
 let's keep this small and simple! If we decide that we need a QMP interface,
 we can do that with a separate patch later.

 v2:
 - Renamed deprecation_msg to deprecation_reason
 - Added information about that field to the MachineClass comment

 hw/i386/pc_piix.c   | 2 ++
 include/hw/boards.h | 4 ++++
 qemu-doc.texi       | 5 +++++
 vl.c                | 9 +++++++--
 4 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index e9b6f06..b4fd164 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -956,6 +956,8 @@ static void pc_i440fx_0_11_machine_options(MachineClass *m)
 {
     pc_i440fx_0_12_machine_options(m);
     m->hw_version = "0.11";
+    m->deprecation_reason = "Old and unsupported machine version, "
+                            "use a newer machine type instead.";
     SET_MACHINE_COMPAT(m, PC_COMPAT_0_11);
 }
 
diff --git a/include/hw/boards.h b/include/hw/boards.h
index ef7457f..6926928 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -107,6 +107,9 @@ typedef struct {
 
 /**
  * MachineClass:
+ * @deprecation_reason: If set, the machine is marked as deprecated. The
+ *    string should give some information about why the machine is deprecated,
+ *    and must provide some clear information about what to use instead.
  * @max_cpus: maximum number of CPUs supported. Default: 1
  * @min_cpus: minimum number of CPUs supported. Default: 1
  * @default_cpus: number of CPUs instantiated if none are specified. Default: 1
@@ -166,6 +169,7 @@ struct MachineClass {
     char *name;
     const char *alias;
     const char *desc;
+    const char *deprecation_reason;
 
     void (*init)(MachineState *state);
     void (*reset)(void);
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 282bc3d..f1dab7e 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -2943,6 +2943,11 @@ support page sizes < 4096 any longer.
 
 @section System emulator machines
 
+@subsection pc-0.10 and pc-0.11 (since 3.0)
+
+These machine types are very old and likely can not be used for live migration
+from old QEMU versions anymore. A newer machine type should be used instead.
+
 @section Device options
 
 @subsection Block device options
diff --git a/vl.c b/vl.c
index b3426e0..7eda6f0 100644
--- a/vl.c
+++ b/vl.c
@@ -2560,8 +2560,9 @@ static gint machine_class_cmp(gconstpointer a, gconstpointer b)
             if (mc->alias) {
                 printf("%-20s %s (alias of %s)\n", mc->alias, mc->desc, mc->name);
             }
-            printf("%-20s %s%s\n", mc->name, mc->desc,
-                   mc->is_default ? " (default)" : "");
+            printf("%-20s %s%s%s\n", mc->name, mc->desc,
+                   mc->is_default ? " (default)" : "",
+                   mc->deprecation_reason ? " (deprecated)" : "");
         }
     }
 
@@ -3953,6 +3954,10 @@ int main(int argc, char **argv, char **envp)
     }
 
     machine_class = select_machine();
+    if (machine_class->deprecation_reason) {
+        error_report("Machine type '%s' is deprecated: %s",
+                     machine_class->name, machine_class->deprecation_reason);
+    }
 
     set_memory_options(&ram_slots, &maxram_size, machine_class);
 
-- 
1.8.3.1

On 21.06.2018 04:18, Thomas Huth wrote:
> The oldest machine type which is still used in a still maintained distro
> is a pc-0.12 based machine type in RHEL6, so everything that is older
> than pc-0.12 should not be used anymore. Thus let's deprecate pc-0.10
> and pc-0.11 so that we can finally remove them in a future release.
[...]
> @@ -3953,6 +3954,10 @@ int main(int argc, char **argv, char **envp)
>      }
>  
>      machine_class = select_machine();
> +    if (machine_class->deprecation_reason) {
> +        error_report("Machine type '%s' is deprecated: %s",
> +                     machine_class->name, machine_class->deprecation_reason);
> +    }

I just noticed that I need to check for !qtest_enabled() here, too,
otherwise these messages show up during "make check". I'll send a v3...

 Thomas