[PULL,2/3] system/vl.c: Print machine name, not "(null)", for unknown machine types

Commit Message

Michael Tokarev Aug. 23, 2024, 2:15 p.m. UTC

From: Peter Maydell <[e-mail]>

In commit 412d294ffdc we tried to improve the error message printed when
the machine type is unknown, but we used the wrong variable, resulting in:

$ ./build/x86/qemu-system-aarch64 -M bang
qemu-system-aarch64: unsupported machine type: "(null)"
Use -machine help to list supported machines

Use the right variable, so we produce more helpful output:

$ ./build/x86/qemu-system-aarch64 -M bang
qemu-system-aarch64: unsupported machine type: "bang"
Use -machine help to list supported machines

Note that we must move the qdict_del() to below the error_setg(),
because machine_type points into the value of that qdict entry,
and deleting it will make the pointer invalid.

Cc: [e-mail]
Fixes: 412d294ffdc ("vl.c: select_machine(): add selected machine type to error message")
Signed-off-by: Peter Maydell <[e-mail]>
Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
Reviewed-by: Michael Tokarev <[e-mail]>
Signed-off-by: Michael Tokarev <[e-mail]>
---
 system/vl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

diff --git a/system/vl.c b/system/vl.c
index 41d53d2456..01b8b8e77a 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -1679,10 +1679,10 @@  static MachineClass *select_machine(QDict *qdict, Error **errp)
 
     if (machine_type) {
         machine_class = find_machine(machine_type, machines);
-        qdict_del(qdict, "type");
         if (!machine_class) {
-            error_setg(errp, "unsupported machine type: \"%s\"", optarg);
+            error_setg(errp, "unsupported machine type: \"%s\"", machine_type);
         }
+        qdict_del(qdict, "type");
     } else {
         machine_class = find_default_machine(machines);
         if (!machine_class) {