3 files changed, 21 insertions, 2 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index da13d6d1b2b0..795c487af8e4 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2150,6 +2150,9 @@ and is between 256 and 4096 characters. It is defined in the file
         usbhid.mousepoll=
                         [USBHID] The interval which mice are to be polled at.
 
+        add_efi_memmap  [EFI; x86-32,X86-64] Include EFI memory map in
+                        kernel's map of available physical RAM.
+
         vdso=           [X86-32,SH,x86-64]
                         vdso=2: enable compat VDSO (default with COMPAT_VDSO)
                         vdso=1: enable VDSO (default)
diff --git a/Documentation/x86/x86_64/uefi.txt b/Documentation/x86/x86_64/uefi.txt
index 7d77120a5184..a5e2b4fdb170 100644
--- a/Documentation/x86/x86_64/uefi.txt
+++ b/Documentation/x86/x86_64/uefi.txt
@@ -36,3 +36,7 @@ Mechanics:
   services.
         noefi           turn off all EFI runtime services
         reboot_type=k   turn off EFI reboot runtime service
+- If the EFI memory map has additional entries not in the E820 map,
+  you can include those entries in the kernels memory map of available
+  physical RAM by using the following kernel command line parameter.
+        add_efi_memmap  include EFI memory map of available physical RAM
diff --git a/arch/x86/kernel/efi.c b/arch/x86/kernel/efi.c
index a03ca36a302c..94382faeadb6 100644
--- a/arch/x86/kernel/efi.c
+++ b/arch/x86/kernel/efi.c
@@ -64,6 +64,17 @@ static int __init setup_noefi(char *arg)
 }
 early_param("noefi", setup_noefi);
 
+int add_efi_memmap;
+EXPORT_SYMBOL(add_efi_memmap);
+
+static int __init setup_add_efi_memmap(char *arg)
+{
+        add_efi_memmap = 1;
+        return 0;
+}
+early_param("add_efi_memmap", setup_add_efi_memmap);
+
+
 static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
 {
         return efi_call_virt2(get_time, tm, tc);
@@ -219,7 +230,7 @@ unsigned long efi_get_time(void)
  * (zeropage) memory map.
  */
 
-static void __init add_efi_memmap(void)
+static void __init do_add_efi_memmap(void)
 {
         void *p;
 
@@ -406,7 +417,8 @@ void __init efi_init(void)
         if (memmap.desc_size != sizeof(efi_memory_desc_t))
                 printk(KERN_WARNING "Kernel-defined memdesc"
                        "doesn't match the one from EFI!\n");
-        add_efi_memmap();
+        if (add_efi_memmap)
+                do_add_efi_memmap();
 
         /* Setup for EFI runtime service */
         reboot_type = BOOT_EFI;