efi: Add "efi_fake_mem" boot option

This patch introduces new boot option named "efi_fake_mem".
By specifying this parameter, you can add arbitrary attribute
to specific memory range.
This is useful for debugging of Address Range Mirroring feature.

For example, if "efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000"
is specified, the original (firmware provided) EFI memmap will be
updated so that the specified memory regions have
EFI_MEMORY_MORE_RELIABLE attribute (0x10000):

 <original>
   efi: mem36: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000100000000-0x00000020a0000000) (129536MB)

 <updated>
   efi: mem36: [Conventional Memory|  |MR|  |  |  |   |WB|WT|WC|UC] range=[0x0000000100000000-0x0000000180000000) (2048MB)
   efi: mem37: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000180000000-0x00000010a0000000) (61952MB)
   efi: mem38: [Conventional Memory|  |MR|  |  |  |   |WB|WT|WC|UC] range=[0x00000010a0000000-0x0000001120000000) (2048MB)
   efi: mem39: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000001120000000-0x00000020a0000000) (63488MB)

And you will find that the following message is output:

   efi: Memory: 4096M/131455M mirrored memory

Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1d6f045..cd5312f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1092,6 +1092,21 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			you are really sure that your UEFI does sane gc and
 			fulfills the spec otherwise your board may brick.
 
+	efi_fake_mem=	nn[KMG]@ss[KMG]:aa[,nn[KMG]@ss[KMG]:aa,..] [EFI; X86]
+			Add arbitrary attribute to specific memory range by
+			updating original EFI memory map.
+			Region of memory which aa attribute is added to is
+			from ss to ss+nn.
+			If efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
+			is specified, EFI_MEMORY_MORE_RELIABLE(0x10000)
+			attribute is added to range 0x100000000-0x180000000 and
+			0x10a0000000-0x1120000000.
+
+			Using this parameter you can do debugging of EFI memmap
+			related feature. For example, you can do debugging of
+			Address Range Mirroring feature even if your box
+			doesn't support it.
+
 	eisa_irq_edge=	[PARISC,HW]
 			See header of drivers/parisc/eisa.c.