qemu: Improve error if setmem fails for lacking of balloon support

"cannot set memory of an active domain" is misleading, it sounds
like setting memory of active domain is not supported.
(cherry picked from commit 968b6c60e9b1889dbaf72cfee1c4fccbd640d69d)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 7d71d7b4d47f66a0a72b1e3d1c41aaa0105963d3..72a91d693f866b5c25e91abc485b9c31bacdcc88 100644 (file)
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -2007,7 +2007,8 @@ static int qemudDomainSetMemoryFlags(virDomainPtr dom, unsigned long newmem,
             /* Lack of balloon support is a fatal error */
             if (r == 0) {
                 qemuReportError(VIR_ERR_OPERATION_INVALID, "%s",
-                                _("cannot set memory of an active domain"));
+                                _("Unable to change memory of active domain without "
+                                  "the balloon device and guest OS balloon driver"));
                 goto endjob;
             }
         }