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From 07742664925f8d055505220258f2589a9c73a80b Mon Sep 17 00:00:00 2001
From: ReddestDream <reddestdream@gmail.com>
Date: Wed, 3 May 2017 00:13:28 -0400
Subject: [PATCH] CbSupportPei: prevent lower coreboot table from being
overwritten
Exclude the bottom 4kb from being included in System Memory HoB
diff --git a/CorebootModulePkg/CbSupportPei/CbSupportPei.c b/CorebootModulePkg/CbSupportPei/CbSupportPei.c
index 262e6b9d7d..da8f060783 100755
--- a/CorebootModulePkg/CbSupportPei/CbSupportPei.c
+++ b/CorebootModulePkg/CbSupportPei/CbSupportPei.c
@@ -246,23 +246,20 @@ CbPeiEntryPoint (
UINTN PmGpeEnBase;
CB_MEM_INFO CbMemInfo;
- //
- // Report lower 640KB of RAM. Attribute EFI_RESOURCE_ATTRIBUTE_TESTED
- // is intentionally omitted to prevent erasing of the coreboot header
- // record before it is processed by CbParseMemoryInfo.
- //
BuildResourceDescriptorHob (
EFI_RESOURCE_SYSTEM_MEMORY,
(
EFI_RESOURCE_ATTRIBUTE_PRESENT |
EFI_RESOURCE_ATTRIBUTE_INITIALIZED |
+ EFI_RESOURCE_ATTRIBUTE_TESTED |
EFI_RESOURCE_ATTRIBUTE_UNCACHEABLE |
EFI_RESOURCE_ATTRIBUTE_WRITE_COMBINEABLE |
EFI_RESOURCE_ATTRIBUTE_WRITE_THROUGH_CACHEABLE |
EFI_RESOURCE_ATTRIBUTE_WRITE_BACK_CACHEABLE
),
- (EFI_PHYSICAL_ADDRESS)(0),
- (UINT64)(0xA0000)
+ // Lower 640KB, except for first 4KB where the lower coreboot pointer ("LBIO") resides
+ (EFI_PHYSICAL_ADDRESS)(0 + 0x1000),
+ (UINT64)(0xA0000 - 0x1000)
);
@@ -309,7 +306,7 @@ CbPeiEntryPoint (
// Set cache on the physical memory
//
MtrrSetMemoryAttribute (BASE_1MB, LowMemorySize - BASE_1MB, CacheWriteBack);
- MtrrSetMemoryAttribute (0, 0xA0000, CacheWriteBack);
+ MtrrSetMemoryAttribute ((0 + 0x1000), (0xA0000 - 0x1000), CacheWriteBack);
//
// Create Memory Type Information HOB
--
2.14.0
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