[Xen-changelog] x86/64 e820-parse-and-map code should skip low 1GB now as that

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 4ce84cc557276466a640c2fa9d4079390fd9bf6c
# Parent  7dc3c0bf1395415979d3dcc4c88e59dc611e2362
x86/64 e820-parse-and-map code should skip low 1GB now as that
is mapped by the boot code.

Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>

diff -r 7dc3c0bf1395 -r 4ce84cc55727 xen/arch/x86/setup.c
--- a/xen/arch/x86/setup.c      Wed Apr 19 22:23:44 2006 +0100
+++ b/xen/arch/x86/setup.c      Wed Apr 19 22:28:22 2006 +0100
@@ -321,7 +321,7 @@ void __init __start_xen(multiboot_info_t
 #if defined (CONFIG_X86_64)
         /*
          * x86/64 maps all registered RAM. Points to note:
-         *  1. The initial pagetable already maps low 64MB, so skip that.
+         *  1. The initial pagetable already maps low 1GB, so skip that.
          *  2. We must map *only* RAM areas, taking care to avoid I/O holes.
          *     Failure to do this can cause coherency problems and deadlocks
          *     due to cache-attribute mismatches (e.g., AMD/AGP Linux bug).
@@ -329,13 +329,14 @@ void __init __start_xen(multiboot_info_t
         {
             /* Calculate page-frame range, discarding partial frames. */
             unsigned long start, end;
+            unsigned long init_mapped = 1UL << (30 - PAGE_SHIFT); /* 1GB */
             start = PFN_UP(e820.map[i].addr);
             end   = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
             /* Clip the range to above 64MB. */
-            if ( end < (64UL << (20-PAGE_SHIFT)) )
+            if ( end < init_mapped )
                 continue;
-            if ( start < (64UL << (20-PAGE_SHIFT)) )
-                start = 64UL << (20-PAGE_SHIFT);
+            if ( start < init_mapped )
+                start = init_mapped;
             /* Request the mapping. */
             map_pages_to_xen(
                 PAGE_OFFSET + (start << PAGE_SHIFT),

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