[Qemu-devel] [PATCH v7] vl.c: Output error on invalid machine type

[mrezanin@redhat.com]

From: Miroslav Rezanina <mrezanin@redhat.com>

Output error message using qemu's error_report() function when user
provides the invalid machine type on the command line. This also saves
time to find what issue is when you downgrade from one version of qemu
to another that doesn't support required machine type yet (the version
user downgraded to have to have this patch applied too, of course).

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
v7:
 - use -machine instead of -M in error help message
 - rebase to commit 0056ae2

v6:
 - print help instead of list supported machines on error
---
 vl.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/vl.c b/vl.c
index 862cf20..cbd1381 100644
--- a/vl.c
+++ b/vl.c
@@ -2649,15 +2649,20 @@ static MachineClass *machine_parse(const char *name)
     if (mc) {
         return mc;
     }
-    printf("Supported machines are:\n");
-    for (el = machines; el; el = el->next) {
-        MachineClass *mc = el->data;
-        QEMUMachine *m = mc->qemu_machine;
-        if (m->alias) {
-            printf("%-20s %s (alias of %s)\n", m->alias, m->desc, m->name);
+    if (name && !is_help_option(name)) {
+        error_report("Unsupported machine type");
+        printf("\nUse -machine help to list supported machines!\n");
+    } else {
+        printf("Supported machines are:\n");
+        for (el = machines; el; el = el->next) {
+            MachineClass *mc = el->data;
+            QEMUMachine *m = mc->qemu_machine;
+            if (m->alias) {
+                printf("%-20s %s (alias of %s)\n", m->alias, m->desc, m->name);
+            }
+            printf("%-20s %s%s\n", m->name, m->desc,
+                   m->is_default ? " (default)" : "");
         }
-        printf("%-20s %s%s\n", m->name, m->desc,
-               m->is_default ? " (default)" : "");
     }
 
     g_slist_free(machines);
-- 
1.8.5.3