2 files changed, 27 insertions, 9 deletions

diff --git a/arch/x86/kernel/e820_64.c b/arch/x86/kernel/e820_64.c
index 8b914a833ac..4a0953857cb 100644
--- a/arch/x86/kernel/e820_64.c
+++ b/arch/x86/kernel/e820_64.c
@@ -621,10 +621,10 @@ static int __init copy_e820_map(struct e820entry *biosmap, int nr_map)
                 return -1;
 
         do {
-                unsigned long start = biosmap->addr;
-                unsigned long size = biosmap->size;
-                unsigned long end = start + size;
-                unsigned long type = biosmap->type;
+                u64 start = biosmap->addr;
+                u64 size = biosmap->size;
+                u64 end = start + size;
+                u32 type = biosmap->type;
 
                 /* Overflow in 64 bits? Ignore the memory map. */
                 if (start > end)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index b684552347d..269a6b481fe 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -55,12 +55,30 @@ static void __init copy_bootdata(char *real_mode_data)
 /*
  * The BIOS places the EBDA/XBDA at the top of conventional
  * memory, and usually decreases the reported amount of
- * conventional memory (int 0x12) too.
+ * conventional memory (int 0x12) too. This also contains a
+ * workaround for Dell systems that neglect to reserve EBDA.
+ * The same workaround also avoids a problem with the AMD768MPX
+ * chipset: reserve a page before VGA to prevent PCI prefetch
+ * into it (errata #56). Usually the page is reserved anyways,
+ * unless you have no PS/2 mouse plugged in.
  */
-static __init void reserve_ebda(void)
+static void __init reserve_ebda_region(void)
 {
         unsigned int lowmem, ebda_addr;
 
+        /* To determine the position of the EBDA and the */
+        /* end of conventional memory, we need to look at */
+        /* the BIOS data area. In a paravirtual environment */
+        /* that area is absent. We'll just have to assume */
+        /* that the paravirt case can handle memory setup */
+        /* correctly, without our help. */
+#ifdef CONFIG_PARAVIRT
+        if ((boot_params.hdr.version >= 0x207) &&
+                        (boot_params.hdr.hardware_subarch != 0)) {
+                return;
+        }
+#endif
+
         /* end of low (conventional) memory */
         lowmem = *(unsigned short *)__va(BIOS_LOWMEM_KILOBYTES);
         lowmem <<= 10;
@@ -80,8 +98,8 @@ static __init void reserve_ebda(void)
                 lowmem = 0x9f000;
 
         /* Paranoia: should never happen, but... */
-        if (lowmem >= 0x100000)
-                lowmem = 0xa0000;
+        if ((lowmem == 0) || (lowmem >= 0x100000))
+                lowmem = 0x9f000;
 
         /* reserve all memory between lowmem and the 1MB mark */
         reserve_early(lowmem, 0x100000, "BIOS reserved");
@@ -140,7 +158,7 @@ void __init x86_64_start_kernel(char * real_mode_data)
                 reserve_early(ramdisk_image, ramdisk_end, "RAMDISK");
         }
 
-        reserve_ebda();
+        reserve_ebda_region();
 
         /*
          * At this point everything still needed from the boot loader