audk/MdePkg/Library/BaseSynchronizationLib/Ia32/InternalGetSpinLockProperties.c
Michael D Kinney 9344f09215 MdePkg: Replace BSD License with BSD+Patent License
https://bugzilla.tianocore.org/show_bug.cgi?id=1373

Replace BSD 2-Clause License with BSD+Patent License.  This change is
based on the following emails:

  https://lists.01.org/pipermail/edk2-devel/2019-February/036260.html
  https://lists.01.org/pipermail/edk2-devel/2018-October/030385.html

RFCs with detailed process for the license change:

  V3: https://lists.01.org/pipermail/edk2-devel/2019-March/038116.html
  V2: https://lists.01.org/pipermail/edk2-devel/2019-March/037669.html
  V1: https://lists.01.org/pipermail/edk2-devel/2019-March/037500.html

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
2019-04-09 10:58:13 -07:00

59 lines
1.3 KiB
C

/** @file
Internal function to get spin lock alignment.
Copyright (c) 2016 - 2018, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "BaseSynchronizationLibInternals.h"
/**
Internal function to retrieve the architecture specific spin lock alignment
requirements for optimal spin lock performance.
@return The architecture specific spin lock alignment.
**/
UINTN
InternalGetSpinLockProperties (
VOID
)
{
UINT32 RegEax;
UINT32 RegEbx;
UINTN FamilyId;
UINTN ModelId;
UINTN CacheLineSize;
//
// Retrieve CPUID Version Information
//
AsmCpuid (0x01, &RegEax, &RegEbx, NULL, NULL);
//
// EBX: Bits 15 - 08: CLFLUSH line size (Value * 8 = cache line size)
//
CacheLineSize = ((RegEbx >> 8) & 0xff) * 8;
//
// Retrieve CPU Family and Model
//
FamilyId = (RegEax >> 8) & 0xf;
ModelId = (RegEax >> 4) & 0xf;
if (FamilyId == 0x0f) {
//
// In processors based on Intel NetBurst microarchitecture, use two cache lines
//
ModelId = ModelId | ((RegEax >> 12) & 0xf0);
if (ModelId <= 0x04 || ModelId == 0x06) {
CacheLineSize *= 2;
}
}
if (CacheLineSize < 32) {
CacheLineSize = 32;
}
return CacheLineSize;
}