[PATCH v3 11/11] machine: Improve error message when using default RAM backend id

[David Hildenbrand <david@redhat.com>]

For migration purposes, users might want to reuse the default RAM
backend id, but specify a different memory backend.

For example, to reuse "pc.ram" on q35, one has to set
    -machine q35,memory-backend=pc.ram
Only then, can a memory backend with the id "pc.ram" be created
manually.

Let's improve the error message.

Unfortuantely, we cannot use error_append_hint(), because the caller
passes &error_fatal.

Suggested-by: ThinerLogoer <logoerthiner1@163.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/core/machine.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index f0d35c6401..dbcd124d45 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -1382,7 +1382,9 @@ void machine_run_board_init(MachineState *machine, const char *mem_path, Error *
                                  machine_class->default_ram_id)) {
             error_setg(errp, "object name '%s' is reserved for the default"
                 " RAM backend, it can't be used for any other purposes."
-                " Change the object's 'id' to something else",
+                " Change the object's 'id' to something else or disable"
+                " automatic creation of the default RAM backend by setting"
+                " the 'memory-backend' machine property",
                 machine_class->default_ram_id);
             return;
         }
-- 
2.41.0