linux-kernel - [PATCH][REVISED] x86: efi/e820 table merge fix

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Message-Id: <E1MH0jo-0001Kp-O3@eag09.americas.sgi.com>
Date:	Wed, 17 Jun 2009 14:24:00 -0500
From:	Cliff Wickman <cpw@....com>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu, hpa@...or.com, ying.huang@...el.com,
	yinghai@...nel.org
Subject: [PATCH][REVISED] x86: efi/e820 table merge fix

From: Cliff Wickman <cpw@....com>

This patch causes all the RAM reservations of EFI_RESERVED_TYPE
to be recorded in the e820 table as type E820_RESERVED.

(A bit of clarification was added in the comment, per Peter and Huang.)

Without this patch EFI_RESERVED_TYPE memory reservations that are also
of attribute type EFI_MEMORY_WB are marked usable in the e820 table.
That would cause a collision between kernel use and some reserver's use
of this memory.

(An example use of this functionality is the UV system, which
 will access extremely large areas of (write-back) memory with a memory
 engine that allows a user to address beyond the processor's range.
 Such areas are reserved in the EFI table by the BIOS.
 Some loaders have a restricted number of entries possible in the e820 table,
 hence the need to record the reservations in the unrestricted EFI table.)

The call to do_add_efi_memmap() is only made if "add_efi_memmap" is specified
on the kernel command line.

Diffed against 2.6.30-rc8

Signed-off-by: Cliff Wickman <cpw@....com>
---
 arch/x86/kernel/efi.c |   35 ++++++++++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)

Index: linux/arch/x86/kernel/efi.c
===================================================================
--- linux.orig/arch/x86/kernel/efi.c
+++ linux/arch/x86/kernel/efi.c
@@ -240,10 +240,39 @@ static void __init do_add_efi_memmap(voi
 		unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
 		int e820_type;
 
-		if (md->attribute & EFI_MEMORY_WB)
-			e820_type = E820_RAM;
-		else
+		switch (md->type) {
+		case EFI_LOADER_CODE:
+		case EFI_LOADER_DATA:
+		case EFI_BOOT_SERVICES_CODE:
+		case EFI_BOOT_SERVICES_DATA:
+		case EFI_CONVENTIONAL_MEMORY:
+			/*
+			 * make sure that memory that is not write-back does
+			 * not enter the usable memory pool
+			 */
+			if (md->attribute & EFI_MEMORY_WB)
+				e820_type = E820_RAM;
+			else
+				e820_type = E820_RESERVED;
+			break;
+		case EFI_ACPI_RECLAIM_MEMORY:
+			e820_type = E820_ACPI;
+			break;
+		case EFI_ACPI_MEMORY_NVS:
+			e820_type = E820_NVS;
+			break;
+		case EFI_UNUSABLE_MEMORY:
+			e820_type = E820_UNUSABLE;
+			break;
+		default:
+			/*
+			 * EFI_RESERVED_TYPE EFI_RUNTIME_SERVICES_CODE
+			 * EFI_RUNTIME_SERVICES_DATA EFI_MEMORY_MAPPED_IO
+			 * EFI_MEMORY_MAPPED_IO_PORT_SPACE EFI_PAL_CODE
+			 */
 			e820_type = E820_RESERVED;
+			break;
+		}
 		e820_add_region(start, size, e820_type);
 	}
 	sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
--
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