pc: Save size of RAM below 4GB

The ram_below_4g value will be useful in other places, such as the ACPI
table code, and other code that currently requires passing
below_4g_mem_size around in function arguments.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 92eabeb..3e1e81b 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -35,7 +35,7 @@
 struct PcGuestInfo {
     bool has_pci_info;
     bool isapc_ram_fw;
-    hwaddr ram_size;
+    hwaddr ram_size, ram_size_below_4g;
     unsigned apic_id_limit;
     bool apic_xrupt_override;
     uint64_t numa_nodes;