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Diffstat (limited to 'hw/i386/pc_piix.c')
-rw-r--r--hw/i386/pc_piix.c19
1 files changed, 17 insertions, 2 deletions
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 4e0dae7981..276641436e 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -61,6 +61,11 @@ static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
 static bool has_pci_info;
 static bool has_acpi_build = true;
 static bool smbios_type1_defaults = true;
+/* Make sure that guest addresses aligned at 1Gbyte boundaries get mapped to
+ * host addresses aligned at 1Gbyte boundaries.  This way we can use 1GByte
+ * pages in the host.
+ */
+static bool gigabyte_align = true;
 
 /* PC hardware initialisation */
 static void pc_init1(QEMUMachineInitArgs *args,
@@ -106,9 +111,17 @@ static void pc_init1(QEMUMachineInitArgs *args,
         kvmclock_create();
     }
 
+    /* Check whether RAM fits below 4G (leaving 1/2 GByte for IO memory).
+     * If it doesn't, we need to split it in chunks below and above 4G.
+     * In any case, try to make sure that guest addresses aligned at
+     * 1G boundaries get mapped to host addresses aligned at 1G boundaries.
+     * For old machine types, use whatever split we used historically to avoid
+     * breaking migration.
+     */
     if (args->ram_size >= 0xe0000000) {
-        above_4g_mem_size = args->ram_size - 0xe0000000;
-        below_4g_mem_size = 0xe0000000;
+        ram_addr_t lowmem = gigabyte_align ? 0xc0000000 : 0xe0000000;
+        above_4g_mem_size = args->ram_size - lowmem;
+        below_4g_mem_size = lowmem;
     } else {
         above_4g_mem_size = 0;
         below_4g_mem_size = args->ram_size;
@@ -157,6 +170,7 @@ static void pc_init1(QEMUMachineInitArgs *args,
     if (pci_enabled) {
         pci_bus = i440fx_init(&i440fx_state, &piix3_devfn, &isa_bus, gsi,
                               system_memory, system_io, args->ram_size,
+                              below_4g_mem_size,
                               above_4g_mem_size,
                               pci_memory, ram_memory);
     } else {
@@ -245,6 +259,7 @@ static void pc_init_pci(QEMUMachineInitArgs *args)
 static void pc_compat_1_7(QEMUMachineInitArgs *args)
 {
     smbios_type1_defaults = false;
+    gigabyte_align = false;
 }
 
 static void pc_compat_1_6(QEMUMachineInitArgs *args)