PPC: mpc8554ds: Tell user about exceeding RAM limits

The mpc8544ds board only supports up to 3GB of RAM due to its limited
address space.

When the user requests more, abort and tell him that he should use less.
Signed-off-by: NAlexander Graf <agraf@suse.de>

hw/ppc/mpc8544ds.c

@@ -15,6 +15,7 @@
 #include "hw/boards.h"
 #include "sysemu/device_tree.h"
 #include "hw/ppc/openpic.h"
+#include "qemu/error-report.h"
 
 static void mpc8544ds_fixup_devtree(PPCE500Params *params, void *fdt)
 {
@@ -38,6 +39,11 @@ static void mpc8544ds_init(MachineState *machine)
         .spin_base = 0xEF000000ULL,
     };
 
+    if (machine->ram_size > 0xc0000000) {
+        error_report("The MPC8544DS board only supports up to 3GB of RAM");
+        exit(1);
+    }
+
     ppce500_init(machine, &params);
 }