ppc/pnv: Set default RAM size to 1 GB

The memory layout of the PowerNV machine is defined as :

  #define KERNEL_LOAD_BASE	((void *)0x20000000)
  #define KERNEL_LOAD_SIZE	0x08000000

  #define INITRAMFS_LOAD_BASE	KERNEL_LOAD_BASE + KERNEL_LOAD_SIZE
  #define INITRAMFS_LOAD_SIZE	0x08000000

  #define SKIBOOT_BASE		0x30000000
  #define SKIBOOT_SIZE		0x01c10000

  #define CPU_STACKS_BASE	(SKIBOOT_BASE + SKIBOOT_SIZE)
  #define STACK_SHIFT		15
  #define STACK_SIZE		(1 << STACK_SHIFT)

The overall size of the CPU stacks is (max PIR + 1) * 32K and the
machine easily reaches 800MB of minimum required RAM.

Any value below will result in a skiboot crash :

    [    0.034949905,3] MEM: Partial overlap detected between regions:
    [    0.034959039,3] MEM: ibm,firmware-stacks [0x31c10000-0x3a450000] (new)
    [    0.034968576,3] MEM: ibm,firmware-allocs-memory@0 [0x31c10000-0x38400000]
    [    0.034980367,3] Out of memory adding skiboot reserved areas
    [    0.035074945,3] ***********************************************
    [    0.035093627,3] < assert failed at core/mem_region.c:1129 >
    [    0.035104247,3]     .
    [    0.035108025,3]      .
    [    0.035111651,3]       .
    [    0.035115231,3]         OO__)
    [    0.035119198,3]        <"__/
    [    0.035122980,3]         ^ ^

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20210129111719.790692-1-clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/pnv.c

@@ -21,6 +21,7 @@
 #include "qemu-common.h"
 #include "qemu/datadir.h"
 #include "qemu/units.h"
+#include "qemu/cutils.h"
 #include "qapi/error.h"
 #include "sysemu/qtest.h"
 #include "sysemu/sysemu.h"
@@ -725,8 +726,11 @@ static void pnv_init(MachineState *machine)
     DeviceState *dev;
 
     /* allocate RAM */
-    if (machine->ram_size < (1 * GiB)) {
-        warn_report("skiboot may not work with < 1GB of RAM");
+    if (machine->ram_size < mc->default_ram_size) {
+        char *sz = size_to_str(mc->default_ram_size);
+        error_report("Invalid RAM size, should be bigger than %s", sz);
+        g_free(sz);
+        exit(EXIT_FAILURE);
     }
     memory_region_add_subregion(get_system_memory(), 0, machine->ram);
 
@@ -1994,7 +1998,7 @@ static void pnv_machine_class_init(ObjectClass *oc, void *data)
      * RAM defaults to less than 2048 for 32-bit hosts, and large
      * enough to fit the maximum initrd size at it's load address
      */
-    mc->default_ram_size = INITRD_LOAD_ADDR + INITRD_MAX_SIZE;
+    mc->default_ram_size = 1 * GiB;
     mc->default_ram_id = "pnv.ram";
     ispc->print_info = pnv_pic_print_info;
     nc->nmi_monitor_handler = pnv_nmi;