[Xen-devel] [PATCH] x86/setup: don't relocate the VGA hole

[Tim Deegan <tim@xxxxxxx>]

# HG changeset patch
# User Tim Deegan <tim@xxxxxxx>
# Date 1360259288 0
# Node ID 7feb83e3f79a3094e3002560c896a9ee97f1e907
# Parent  6c1b12c884b4521a940e079c8dfebc5d8e88d2e9
x86/setup: don't relocate the VGA hole.

Copying the contents of the VGA hole is at best pointless and at worst
dangerous.  Booting Xen on Xen, it causes a very long delay as each
byte is referred to qemu.

Since we were already discarding the first 1MB of the relocated area,
just avoid copying it in the first place.

Reported-by: Jon Ludlam <jonathan.ludlam@xxxxxxxxxxxxx>
Signed-off-by: Tim Deegan <tim@xxxxxxx>

diff -r 6c1b12c884b4 -r 7feb83e3f79a xen/arch/x86/setup.c
--- a/xen/arch/x86/setup.c      Tue Feb 05 15:47:41 2013 +0000
+++ b/xen/arch/x86/setup.c      Thu Feb 07 17:48:08 2013 +0000
@@ -826,7 +826,6 @@ void __init __start_xen(unsigned long mb
             l3_pgentry_t *pl3e;
             l2_pgentry_t *pl2e;
             int i, j, k;
-            void *dst;
 
             /* Select relocation address. */
             e = end - reloc_size;
@@ -840,10 +839,8 @@ void __init __start_xen(unsigned long mb
              * data until after we have switched to the relocated pagetables!
              */
             barrier();
-            dst = move_memory(e, 0, (unsigned long)&_end - XEN_VIRT_START, 1);
-
-            /* Poison low 1MB to detect stray pointers to physical 0-1MB. */
-            memset(dst, 0x55, 1U << 20);
+            move_memory(e + (1u << 20), (1u << 20),
+                      ((unsigned long)&_end - XEN_VIRT_START) - (1u << 20), 1);
 
             /* Walk initial pagetables, relocating page directory entries. */
             pl4e = __va(__pa(idle_pg_table));

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