File 25786-x86-prefer-multiboot-meminfo-over-e801.patch of Package xen.openSUSE_12.1_Update

# HG changeset patch
# User Keir Fraser <keir@xen.org>
# Date 1346190045 -3600
# Node ID a0b5f8102a0013c112d8e2f7c476040e882838ae
# Parent  3908b256ff345539ae63851b8d3f810d9af19890
x86: Prefer multiboot-provided e820 over bios-provided e801 memory info.

Some UEFI systems do not provide e820 information. In this case we
should take the detailed memory map provided by a multiboot-capable
loader, rather than rely on very conservative values from the e801
bios call. Using the latter on any modern system really hardly makes
good sense.

[Excellent candidate for 4.1 backport]

Signed-off-by: Keir Fraser <keir@xen.org>
Tested-by: Jonathan Tripathy <jonnyt@abpni.co.uk>

--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -691,17 +691,6 @@ void __init __start_xen(unsigned long mb
     {
         memmap_type = "Xen-e820";
     }
-    else if ( bootsym(lowmem_kb) )
-    {
-        memmap_type = "Xen-e801";
-        e820_raw[0].addr = 0;
-        e820_raw[0].size = bootsym(lowmem_kb) << 10;
-        e820_raw[0].type = E820_RAM;
-        e820_raw[1].addr = 0x100000;
-        e820_raw[1].size = bootsym(highmem_kb) << 10;
-        e820_raw[1].type = E820_RAM;
-        e820_raw_nr = 2;
-    }
     else if ( mbi->flags & MBI_MEMMAP )
     {
         memmap_type = "Multiboot-e820";
@@ -739,6 +728,17 @@ void __init __start_xen(unsigned long mb
             bytes += map->size + 4;
         }
     }
+    else if ( bootsym(lowmem_kb) )
+    {
+        memmap_type = "Xen-e801";
+        e820_raw[0].addr = 0;
+        e820_raw[0].size = bootsym(lowmem_kb) << 10;
+        e820_raw[0].type = E820_RAM;
+        e820_raw[1].addr = 0x100000;
+        e820_raw[1].size = bootsym(highmem_kb) << 10;
+        e820_raw[1].type = E820_RAM;
+        e820_raw_nr = 2;
+    }
     else if ( mbi->flags & MBI_MEMLIMITS )
     {
         memmap_type = "Multiboot-e801";