[PATCH v3 3/3] RFC: OvmfPkg/PlatformPei: stop using cmos for memory detection


Gerd Hoffmann
 

Not needed for qemu 1.7 (released in 2013) and newer.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3593
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
OvmfPkg/PlatformPei/MemDetect.c | 59 +++------------------------------
1 file changed, 4 insertions(+), 55 deletions(-)

diff --git a/OvmfPkg/PlatformPei/MemDetect.c b/OvmfPkg/PlatformPei/MemDetect.c
index 1d942b12d519..778d150e956b 100644
--- a/OvmfPkg/PlatformPei/MemDetect.c
+++ b/OvmfPkg/PlatformPei/MemDetect.c
@@ -37,7 +37,6 @@ Module Name:
#include <Library/QemuFwCfgSimpleParserLib.h>

#include "Platform.h"
-#include "Cmos.h"

UINT8 mPhysMemAddressWidth;

@@ -295,52 +294,12 @@ GetSystemMemorySizeBelow4gb (
{
EFI_STATUS Status;
UINT64 LowerMemorySize = 0;
- UINT8 Cmos0x34;
- UINT8 Cmos0x35;

Status = ScanOrAdd64BitE820Ram (FALSE, &LowerMemorySize, NULL);
- if (Status == EFI_SUCCESS && LowerMemorySize > 0) {
- return (UINT32)LowerMemorySize;
- }
+ ASSERT_EFI_ERROR (Status);
+ ASSERT (LowerMemorySize > 0);
+ return (UINT32)LowerMemorySize;

- //
- // CMOS 0x34/0x35 specifies the system memory above 16 MB.
- // * CMOS(0x35) is the high byte
- // * CMOS(0x34) is the low byte
- // * The size is specified in 64kb chunks
- // * Since this is memory above 16MB, the 16MB must be added
- // into the calculation to get the total memory size.
- //
-
- Cmos0x34 = (UINT8) CmosRead8 (0x34);
- Cmos0x35 = (UINT8) CmosRead8 (0x35);
-
- return (UINT32) (((UINTN)((Cmos0x35 << 8) + Cmos0x34) << 16) + SIZE_16MB);
-}
-
-
-STATIC
-UINT64
-GetSystemMemorySizeAbove4gb (
- )
-{
- UINT32 Size;
- UINTN CmosIndex;
-
- //
- // CMOS 0x5b-0x5d specifies the system memory above 4GB MB.
- // * CMOS(0x5d) is the most significant size byte
- // * CMOS(0x5c) is the middle size byte
- // * CMOS(0x5b) is the least significant size byte
- // * The size is specified in 64kb chunks
- //
-
- Size = 0;
- for (CmosIndex = 0x5d; CmosIndex >= 0x5b; CmosIndex--) {
- Size = (UINT32) (Size << 8) + (UINT32) CmosRead8 (CmosIndex);
- }
-
- return LShiftU64 (Size, 16);
}


@@ -371,12 +330,9 @@ GetFirstNonAddress (
// If QEMU presents an E820 map, then get the highest exclusive >=4GB RAM
// address from it. This can express an address >= 4GB+1TB.
//
- // Otherwise, get the flat size of the memory above 4GB from the CMOS (which
- // can only express a size smaller than 1TB), and add it to 4GB.
- //
Status = ScanOrAdd64BitE820Ram (FALSE, NULL, &FirstNonAddress);
if (EFI_ERROR (Status)) {
- FirstNonAddress = BASE_4GB + GetSystemMemorySizeAbove4gb ();
+ FirstNonAddress = BASE_4GB;
}

//
@@ -719,7 +675,6 @@ QemuInitializeRam (
)
{
UINT64 LowerMemorySize;
- UINT64 UpperMemorySize;
MTRR_SETTINGS MtrrSettings;
EFI_STATUS Status;

@@ -775,12 +730,6 @@ QemuInitializeRam (
// memory size read from the CMOS.
//
Status = ScanOrAdd64BitE820Ram (TRUE, NULL, NULL);
- if (EFI_ERROR (Status)) {
- UpperMemorySize = GetSystemMemorySizeAbove4gb ();
- if (UpperMemorySize != 0) {
- AddMemoryBaseSizeHob (BASE_4GB, UpperMemorySize);
- }
- }
}

//
--
2.31.1