xen: do not create the extra e820 region at an addr lower than 4G

Do not add the extra e820 region at a physical address lower than 4G
because it breaks e820_end_of_low_ram_pfn().

It is OK for us to move the xen_extra_mem_start up and down because this
is the index of the memory that can be ballooned in/out - it is memory
not available to the kernel during bootup.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 9c38bd1b149ddea3e9e3160d7044049329a1439f..a51e010833b41f20148ad20893db524e75b5fa62 100644 (file)
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -229,7 +229,7 @@ char * __init xen_memory_setup(void)
 
        memcpy(map_raw, map, sizeof(map));
        e820.nr_map = 0;
-       xen_extra_mem_start = mem_end;
+       xen_extra_mem_start = max((1ULL << 32), mem_end);
        for (i = 0; i < memmap.nr_entries; i++) {
                unsigned long long end;