x86: update mptable

make mptable to be consistent with acpi routing, so we could:

1. kexec kernel with acpi=off
2. work around BIOSes where acpi routing is working, but mptable is
   not right, so can use kernel/kexec to start other OSes that don't have
   good acpi support.

command line: update_mptable

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 25 insertions, 0 deletions

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 0cd9132c9450..cd2b99e27d43 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -739,3 +739,28 @@ u64 __init find_e820_area_size(u64 start, u64 *sizep, u64 align)
         return -1UL;
 
 }
+
+/*
+ * pre allocated 4k and reserved it in e820
+ */
+u64 __init early_reserve_e820(u64 startt, u64 sizet, u64 align)
+{
+        u64 size = 0;
+        u64 addr;
+        u64 start;
+
+        start = startt;
+        while (size < sizet)
+                start = find_e820_area_size(start, &size, align);
+
+        if (size < sizet)
+                return 0;
+
+        addr = round_down(start + size - sizet, align);
+        update_memory_range(addr, sizet, E820_RAM, E820_RESERVED);
+        printk(KERN_INFO "update e820 for early_reserve_e820\n");
+        update_e820();
+
+        return addr;
+}
+