Renormalized end-of-lines from master@27b044605cd5f6b33a3d231576003850b3fe305btrunk

3 files changed, 1410 insertions, 1410 deletions

diff --git a/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/DxeDebugAgentLib.c b/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/DxeDebugAgentLib.c
index a41bba2c4b..7bea778378 100644
--- a/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/DxeDebugAgentLib.c
+++ b/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/DxeDebugAgentLib.c
@@ -1,549 +1,549 @@
-/** @file

-  Debug Agent library implementation for Dxe Core and Dxr modules.

-

-  Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>

-  SPDX-License-Identifier: BSD-2-Clause-Patent

-

-**/

-

-#include "DxeDebugAgentLib.h"

-

-DEBUG_AGENT_MAILBOX       mMailbox;

-DEBUG_AGENT_MAILBOX       *mMailboxPointer = NULL;

-IA32_IDT_GATE_DESCRIPTOR  mIdtEntryTable[33];

-BOOLEAN                   mDxeCoreFlag                = FALSE;

-BOOLEAN                   mMultiProcessorDebugSupport = FALSE;

-VOID                      *mSavedIdtTable             = NULL;

-UINTN                     mSaveIdtTableSize           = 0;

-BOOLEAN                   mDebugAgentInitialized      = FALSE;

-BOOLEAN                   mSkipBreakpoint             = FALSE;

-

-/**

-  Check if debug agent support multi-processor.

-

-  @retval TRUE    Multi-processor is supported.

-  @retval FALSE   Multi-processor is not supported.

-

-**/

-BOOLEAN

-MultiProcessorDebugSupport (

-  VOID

-  )

-{

-  return mMultiProcessorDebugSupport;

-}

-

-/**

-  Internal constructor worker function.

-

-  It will register one callback function on EFI PCD Protocol.

-  It will allocate the NVS memory to store Mailbox and install configuration table

-  in system table to store its pointer.

-

-**/

-VOID

-InternalConstructorWorker (

-  VOID

-  )

-{

-  EFI_STATUS               Status;

-  EFI_PHYSICAL_ADDRESS     Address;

-  BOOLEAN                  DebugTimerInterruptState;

-  DEBUG_AGENT_MAILBOX      *Mailbox;

-  DEBUG_AGENT_MAILBOX      *NewMailbox;

-  EFI_HOB_GUID_TYPE        *GuidHob;

-  EFI_VECTOR_HANDOFF_INFO  *VectorHandoffInfo;

-

-  //

-  // Check persisted vector handoff info

-  //

-  Status  = EFI_SUCCESS;

-  GuidHob = GetFirstGuidHob (&gEfiVectorHandoffInfoPpiGuid);

-  if ((GuidHob != NULL) && !mDxeCoreFlag) {

-    //

-    // Check if configuration table is installed or not if GUIDed HOB existed,

-    // only when Debug Agent is not linked by DXE Core

-    //

-    Status = EfiGetSystemConfigurationTable (&gEfiVectorHandoffTableGuid, (VOID **)&VectorHandoffInfo);

-  }

-

-  if ((GuidHob == NULL) || (Status != EFI_SUCCESS)) {

-    //

-    // Install configuration table for persisted vector handoff info if GUIDed HOB cannot be found or

-    // configuration table does not exist

-    //

-    Status = gBS->InstallConfigurationTable (&gEfiVectorHandoffTableGuid, (VOID *)&mVectorHandoffInfoDebugAgent[0]);

-    if (EFI_ERROR (Status)) {

-      DEBUG ((DEBUG_ERROR, "DebugAgent: Cannot install configuration table for persisted vector handoff info!\n"));

-      CpuDeadLoop ();

-    }

-  }

-

-  //

-  // Install EFI Serial IO protocol on debug port

-  //

-  InstallSerialIo ();

-

-  Address = 0;

-  Status  = gBS->AllocatePages (

-                   AllocateAnyPages,

-                   EfiACPIMemoryNVS,

-                   EFI_SIZE_TO_PAGES (sizeof (DEBUG_AGENT_MAILBOX) + PcdGet16 (PcdDebugPortHandleBufferSize)),

-                   &Address

-                   );

-  if (EFI_ERROR (Status)) {

-    DEBUG ((DEBUG_ERROR, "DebugAgent: Cannot install configuration table for mailbox!\n"));

-    CpuDeadLoop ();

-  }

-

-  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);

-

-  NewMailbox = (DEBUG_AGENT_MAILBOX *)(UINTN)Address;

-  //

-  // Copy Mailbox and Debug Port Handle buffer to new location in ACPI NVS memory, because original Mailbox

-  // and Debug Port Handle buffer may be free at runtime, SMM debug agent needs to access them

-  //

-  Mailbox = GetMailboxPointer ();

-  CopyMem (NewMailbox, Mailbox, sizeof (DEBUG_AGENT_MAILBOX));

-  CopyMem (NewMailbox + 1, (VOID *)(UINTN)Mailbox->DebugPortHandle, PcdGet16 (PcdDebugPortHandleBufferSize));

-  //

-  // Update Debug Port Handle in new Mailbox

-  //

-  UpdateMailboxContent (NewMailbox, DEBUG_MAILBOX_DEBUG_PORT_HANDLE_INDEX, (UINT64)(UINTN)(NewMailbox + 1));

-  mMailboxPointer = NewMailbox;

-

-  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);

-

-  Status = gBS->InstallConfigurationTable (&gEfiDebugAgentGuid, (VOID *)mMailboxPointer);

-  if (EFI_ERROR (Status)) {

-    DEBUG ((DEBUG_ERROR, "DebugAgent: Failed to install configuration for mailbox!\n"));

-    CpuDeadLoop ();

-  }

-}

-

-/**

-  Debug Agent constructor function.

-

-  @param[in]  ImageHandle   The firmware allocated handle for the EFI image.

-  @param[in]  SystemTable   A pointer to the EFI System Table.

-

-  @retval  RETURN_SUCCESS  When this function completed.

-

-**/

-RETURN_STATUS

-EFIAPI

-DxeDebugAgentLibConstructor (

-  IN EFI_HANDLE        ImageHandle,

-  IN EFI_SYSTEM_TABLE  *SystemTable

-  )

-{

-  if (mDxeCoreFlag) {

-    //

-    // Invoke internal constructor function only when DXE core links this library instance

-    //

-    InternalConstructorWorker ();

-  }

-

-  return RETURN_SUCCESS;

-}

-

-/**

-  Get the pointer to Mailbox from the configuration table.

-

-  @return Pointer to Mailbox.

-

-**/

-DEBUG_AGENT_MAILBOX *

-GetMailboxFromConfigurationTable (

-  VOID

-  )

-{

-  EFI_STATUS           Status;

-  DEBUG_AGENT_MAILBOX  *Mailbox;

-

-  Status = EfiGetSystemConfigurationTable (&gEfiDebugAgentGuid, (VOID **)&Mailbox);

-  if ((Status == EFI_SUCCESS) && (Mailbox != NULL)) {

-    VerifyMailboxChecksum (Mailbox);

-    return Mailbox;

-  } else {

-    return NULL;

-  }

-}

-

-/**

-  Get the pointer to Mailbox from the GUIDed HOB.

-

-  @param[in]  HobStart      The starting HOB pointer to search from.

-

-  @return Pointer to Mailbox.

-

-**/

-DEBUG_AGENT_MAILBOX *

-GetMailboxFromHob (

-  IN VOID  *HobStart

-  )

-{

-  EFI_HOB_GUID_TYPE    *GuidHob;

-  UINT64               *MailboxLocation;

-  DEBUG_AGENT_MAILBOX  *Mailbox;

-

-  GuidHob = GetNextGuidHob (&gEfiDebugAgentGuid, HobStart);

-  if (GuidHob == NULL) {

-    return NULL;

-  }

-

-  MailboxLocation = (UINT64 *)(GET_GUID_HOB_DATA (GuidHob));

-  Mailbox         = (DEBUG_AGENT_MAILBOX *)(UINTN)(*MailboxLocation);

-  VerifyMailboxChecksum (Mailbox);

-

-  return Mailbox;

-}

-

-/**

-  Get Debug Agent Mailbox pointer.

-

-  @return Mailbox pointer.

-

-**/

-DEBUG_AGENT_MAILBOX *

-GetMailboxPointer (

-  VOID

-  )

-{

-  AcquireMpSpinLock (&mDebugMpContext.MailboxSpinLock);

-  VerifyMailboxChecksum (mMailboxPointer);

-  ReleaseMpSpinLock (&mDebugMpContext.MailboxSpinLock);

-  return mMailboxPointer;

-}

-

-/**

-  Get debug port handle.

-

-  @return Debug port handle.

-

-**/

-DEBUG_PORT_HANDLE

-GetDebugPortHandle (

-  VOID

-  )

-{

-  return (DEBUG_PORT_HANDLE)(UINTN)(GetMailboxPointer ()->DebugPortHandle);

-}

-

-/**

-  Worker function to set up Debug Agent environment.

-

-  This function will set up IDT table and initialize the IDT entries and

-  initialize CPU LOCAL APIC timer.

-  It also tries to connect HOST if Debug Agent was not initialized before.

-

-  @param[in] Mailbox        Pointer to Mailbox.

-

-**/

-VOID

-SetupDebugAgentEnvironment (

-  IN DEBUG_AGENT_MAILBOX  *Mailbox

-  )

-{

-  IA32_DESCRIPTOR  Idtr;

-  UINT16           IdtEntryCount;

-  UINT64           DebugPortHandle;

-  UINT32           DebugTimerFrequency;

-

-  if (mMultiProcessorDebugSupport) {

-    InitializeSpinLock (&mDebugMpContext.MpContextSpinLock);

-    InitializeSpinLock (&mDebugMpContext.DebugPortSpinLock);

-    InitializeSpinLock (&mDebugMpContext.MailboxSpinLock);

-    //

-    // Clear Break CPU index value

-    //

-    mDebugMpContext.BreakAtCpuIndex = (UINT32)-1;

-  }

-

-  //

-  // Get original IDT address and size.

-  //

-  AsmReadIdtr ((IA32_DESCRIPTOR *)&Idtr);

-  IdtEntryCount = (UINT16)((Idtr.Limit + 1) / sizeof (IA32_IDT_GATE_DESCRIPTOR));

-  if (IdtEntryCount < 33) {

-    ZeroMem (&mIdtEntryTable, sizeof (IA32_IDT_GATE_DESCRIPTOR) * 33);

-    //

-    // Copy original IDT table into new one

-    //

-    CopyMem (&mIdtEntryTable, (VOID *)Idtr.Base, Idtr.Limit + 1);

-    //

-    // Load new IDT table

-    //

-    Idtr.Limit = (UINT16)(sizeof (IA32_IDT_GATE_DESCRIPTOR) * 33 - 1);

-    Idtr.Base  = (UINTN)&mIdtEntryTable;

-    AsmWriteIdtr ((IA32_DESCRIPTOR *)&Idtr);

-  }

-

-  //

-  // Initialize the IDT table entries to support source level debug.

-  //

-  InitializeDebugIdt ();

-

-  //

-  // If mMailboxPointer is not set before, set it

-  //

-  if (mMailboxPointer == NULL) {

-    if (Mailbox != NULL) {

-      //

-      // If Mailbox exists, copy it into one global variable

-      //

-      CopyMem (&mMailbox, Mailbox, sizeof (DEBUG_AGENT_MAILBOX));

-    } else {

-      ZeroMem (&mMailbox, sizeof (DEBUG_AGENT_MAILBOX));

-    }

-

-    mMailboxPointer = &mMailbox;

-  }

-

-  //

-  // Initialize Debug Timer hardware and save its initial count and frequency

-  //

-  mDebugMpContext.DebugTimerInitCount = InitializeDebugTimer (&DebugTimerFrequency, TRUE);

-  UpdateMailboxContent (mMailboxPointer, DEBUG_MAILBOX_DEBUG_TIMER_FREQUENCY, DebugTimerFrequency);

-  //

-  // Initialize debug communication port

-  //

-  DebugPortHandle = (UINT64)(UINTN)DebugPortInitialize ((VOID *)(UINTN)mMailboxPointer->DebugPortHandle, NULL);

-  UpdateMailboxContent (mMailboxPointer, DEBUG_MAILBOX_DEBUG_PORT_HANDLE_INDEX, DebugPortHandle);

-

-  if (Mailbox == NULL) {

-    //

-    // Trigger one software interrupt to inform HOST

-    //

-    TriggerSoftInterrupt (SYSTEM_RESET_SIGNATURE);

-    SetDebugFlag (DEBUG_AGENT_FLAG_MEMORY_READY, 1);

-    //

-    // Memory has been ready

-    //

-    if (IsHostAttached ()) {

-      //

-      // Trigger one software interrupt to inform HOST

-      //

-      TriggerSoftInterrupt (MEMORY_READY_SIGNATURE);

-    }

-  }

-}

-

-/**

-  Initialize debug agent.

-

-  This function is used to set up debug environment for DXE phase.

-

-  If this function is called by DXE Core, Context must be the pointer

-  to HOB list which will be used to get GUIDed HOB. It will enable

-  interrupt to support break-in feature.

-  If this function is called by DXE module, Context must be NULL. It

-  will enable interrupt to support break-in feature.

-

-  @param[in] InitFlag     Init flag is used to decide initialize process.

-  @param[in] Context      Context needed according to InitFlag.

-  @param[in] Function     Continue function called by debug agent library; it was

-                          optional.

-

-**/

-VOID

-EFIAPI

-InitializeDebugAgent (

-  IN UINT32                InitFlag,

-  IN VOID                  *Context  OPTIONAL,

-  IN DEBUG_AGENT_CONTINUE  Function  OPTIONAL

-  )

-{

-  UINT64               *MailboxLocation;

-  DEBUG_AGENT_MAILBOX  *Mailbox;

-  BOOLEAN              InterruptStatus;

-  VOID                 *HobList;

-  IA32_DESCRIPTOR      IdtDescriptor;

-  IA32_DESCRIPTOR      *Ia32Idtr;

-  IA32_IDT_ENTRY       *Ia32IdtEntry;

-  BOOLEAN              PeriodicMode;

-  UINTN                TimerCycle;

-

-  if (InitFlag == DEBUG_AGENT_INIT_DXE_AP) {

-    //

-    // Check if CPU APIC Timer is working, otherwise initialize it.

-    //

-    InitializeLocalApicSoftwareEnable (TRUE);

-    GetApicTimerState (NULL, &PeriodicMode, NULL);

-    TimerCycle = GetApicTimerInitCount ();

-    if (!PeriodicMode || (TimerCycle == 0)) {

-      InitializeDebugTimer (NULL, FALSE);

-    }

-

-    //

-    // Invoked by AP, enable interrupt to let AP could receive IPI from other processors

-    //

-    EnableInterrupts ();

-    return;

-  }

-

-  //

-  // Disable Debug Timer interrupt

-  //

-  SaveAndSetDebugTimerInterrupt (FALSE);

-  //

-  // Save and disable original interrupt status

-  //

-  InterruptStatus = SaveAndDisableInterrupts ();

-

-  //

-  // Try to get mailbox firstly

-  //

-  HobList         = NULL;

-  Mailbox         = NULL;

-  MailboxLocation = NULL;

-

-  switch (InitFlag) {

-    case DEBUG_AGENT_INIT_DXE_LOAD:

-      //

-      // Check if Debug Agent has been initialized before

-      //

-      if (IsDebugAgentInitialzed ()) {

-        DEBUG ((DEBUG_INFO, "Debug Agent: The former agent will be overwritten by the new one!\n"));

-      }

-

-      mMultiProcessorDebugSupport = TRUE;

-      //

-      // Save original IDT table

-      //

-      AsmReadIdtr (&IdtDescriptor);

-      mSaveIdtTableSize = IdtDescriptor.Limit + 1;

-      mSavedIdtTable    = AllocateCopyPool (mSaveIdtTableSize, (VOID *)IdtDescriptor.Base);

-      //

-      // Check if Debug Agent initialized in DXE phase

-      //

-      Mailbox = GetMailboxFromConfigurationTable ();

-      if (Mailbox == NULL) {

-        //

-        // Try to get mailbox from GUIDed HOB build in PEI

-        //

-        HobList = GetHobList ();

-        Mailbox = GetMailboxFromHob (HobList);

-      }

-

-      //

-      // Set up Debug Agent Environment and try to connect HOST if required

-      //

-      SetupDebugAgentEnvironment (Mailbox);

-      //

-      // For DEBUG_AGENT_INIT_S3, needn't to install configuration table and EFI Serial IO protocol

-      // For DEBUG_AGENT_INIT_DXE_CORE, InternalConstructorWorker() will invoked in Constructor()

-      //

-      InternalConstructorWorker ();

-      //

-      // Enable Debug Timer interrupt

-      //

-      SaveAndSetDebugTimerInterrupt (TRUE);

-      //

-      // Enable interrupt to receive Debug Timer interrupt

-      //

-      EnableInterrupts ();

-

-      mDebugAgentInitialized = TRUE;

-      FindAndReportModuleImageInfo (SIZE_4KB);

-

-      *(EFI_STATUS *)Context = EFI_SUCCESS;

-

-      break;

-

-    case DEBUG_AGENT_INIT_DXE_UNLOAD:

-      if (mDebugAgentInitialized) {

-        if (IsHostAttached ()) {

-          *(EFI_STATUS *)Context = EFI_ACCESS_DENIED;

-          //

-          // Enable Debug Timer interrupt again

-          //

-          SaveAndSetDebugTimerInterrupt (TRUE);

-        } else {

-          //

-          // Restore original IDT table

-          //

-          AsmReadIdtr (&IdtDescriptor);

-          IdtDescriptor.Limit = (UINT16)(mSaveIdtTableSize - 1);

-          CopyMem ((VOID *)IdtDescriptor.Base, mSavedIdtTable, mSaveIdtTableSize);

-          AsmWriteIdtr (&IdtDescriptor);

-          FreePool (mSavedIdtTable);

-          mDebugAgentInitialized = FALSE;

-          *(EFI_STATUS *)Context = EFI_SUCCESS;

-        }

-      } else {

-        *(EFI_STATUS *)Context = EFI_NOT_STARTED;

-      }

-

-      //

-      // Restore interrupt state.

-      //

-      SetInterruptState (InterruptStatus);

-      break;

-

-    case DEBUG_AGENT_INIT_DXE_CORE:

-      mDxeCoreFlag                = TRUE;

-      mMultiProcessorDebugSupport = TRUE;

-      //

-      // Try to get mailbox from GUIDed HOB build in PEI

-      //

-      HobList = Context;

-      Mailbox = GetMailboxFromHob (HobList);

-      //

-      // Set up Debug Agent Environment and try to connect HOST if required

-      //

-      SetupDebugAgentEnvironment (Mailbox);

-      //

-      // Enable Debug Timer interrupt

-      //

-      SaveAndSetDebugTimerInterrupt (TRUE);

-      //

-      // Enable interrupt to receive Debug Timer interrupt

-      //

-      EnableInterrupts ();

-

-      break;

-

-    case DEBUG_AGENT_INIT_S3:

-

-      if (Context != NULL) {

-        Ia32Idtr        =  (IA32_DESCRIPTOR *)Context;

-        Ia32IdtEntry    = (IA32_IDT_ENTRY *)(Ia32Idtr->Base);

-        MailboxLocation = (UINT64 *)((UINTN)Ia32IdtEntry[DEBUG_MAILBOX_VECTOR].Bits.OffsetLow +

-                                     ((UINTN)Ia32IdtEntry[DEBUG_MAILBOX_VECTOR].Bits.OffsetHigh << 16));

-        Mailbox = (DEBUG_AGENT_MAILBOX *)(UINTN)(*MailboxLocation);

-        VerifyMailboxChecksum (Mailbox);

-      }

-

-      //

-      // Save Mailbox pointer in global variable

-      //

-      mMailboxPointer = Mailbox;

-      //

-      // Set up Debug Agent Environment and try to connect HOST if required

-      //

-      SetupDebugAgentEnvironment (Mailbox);

-      //

-      // Disable interrupt

-      //

-      DisableInterrupts ();

-      FindAndReportModuleImageInfo (SIZE_4KB);

-      if (GetDebugFlag (DEBUG_AGENT_FLAG_BREAK_BOOT_SCRIPT) == 1) {

-        //

-        // If Boot Script entry break is set, code will be break at here.

-        //

-        CpuBreakpoint ();

-      }

-

-      break;

-

-    default:

-      //

-      // Only DEBUG_AGENT_INIT_PREMEM_SEC and DEBUG_AGENT_INIT_POSTMEM_SEC are allowed for this

-      // Debug Agent library instance.

-      //

-      DEBUG ((DEBUG_ERROR, "Debug Agent: The InitFlag value is not allowed!\n"));

-      CpuDeadLoop ();

-      break;

-  }

-}

+/** @file
+  Debug Agent library implementation for Dxe Core and Dxr modules.
+
+  Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "DxeDebugAgentLib.h"
+
+DEBUG_AGENT_MAILBOX       mMailbox;
+DEBUG_AGENT_MAILBOX       *mMailboxPointer = NULL;
+IA32_IDT_GATE_DESCRIPTOR  mIdtEntryTable[33];
+BOOLEAN                   mDxeCoreFlag                = FALSE;
+BOOLEAN                   mMultiProcessorDebugSupport = FALSE;
+VOID                      *mSavedIdtTable             = NULL;
+UINTN                     mSaveIdtTableSize           = 0;
+BOOLEAN                   mDebugAgentInitialized      = FALSE;
+BOOLEAN                   mSkipBreakpoint             = FALSE;
+
+/**
+  Check if debug agent support multi-processor.
+
+  @retval TRUE    Multi-processor is supported.
+  @retval FALSE   Multi-processor is not supported.
+
+**/
+BOOLEAN
+MultiProcessorDebugSupport (
+  VOID
+  )
+{
+  return mMultiProcessorDebugSupport;
+}
+
+/**
+  Internal constructor worker function.
+
+  It will register one callback function on EFI PCD Protocol.
+  It will allocate the NVS memory to store Mailbox and install configuration table
+  in system table to store its pointer.
+
+**/
+VOID
+InternalConstructorWorker (
+  VOID
+  )
+{
+  EFI_STATUS               Status;
+  EFI_PHYSICAL_ADDRESS     Address;
+  BOOLEAN                  DebugTimerInterruptState;
+  DEBUG_AGENT_MAILBOX      *Mailbox;
+  DEBUG_AGENT_MAILBOX      *NewMailbox;
+  EFI_HOB_GUID_TYPE        *GuidHob;
+  EFI_VECTOR_HANDOFF_INFO  *VectorHandoffInfo;
+
+  //
+  // Check persisted vector handoff info
+  //
+  Status  = EFI_SUCCESS;
+  GuidHob = GetFirstGuidHob (&gEfiVectorHandoffInfoPpiGuid);
+  if ((GuidHob != NULL) && !mDxeCoreFlag) {
+    //
+    // Check if configuration table is installed or not if GUIDed HOB existed,
+    // only when Debug Agent is not linked by DXE Core
+    //
+    Status = EfiGetSystemConfigurationTable (&gEfiVectorHandoffTableGuid, (VOID **)&VectorHandoffInfo);
+  }
+
+  if ((GuidHob == NULL) || (Status != EFI_SUCCESS)) {
+    //
+    // Install configuration table for persisted vector handoff info if GUIDed HOB cannot be found or
+    // configuration table does not exist
+    //
+    Status = gBS->InstallConfigurationTable (&gEfiVectorHandoffTableGuid, (VOID *)&mVectorHandoffInfoDebugAgent[0]);
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_ERROR, "DebugAgent: Cannot install configuration table for persisted vector handoff info!\n"));
+      CpuDeadLoop ();
+    }
+  }
+
+  //
+  // Install EFI Serial IO protocol on debug port
+  //
+  InstallSerialIo ();
+
+  Address = 0;
+  Status  = gBS->AllocatePages (
+                   AllocateAnyPages,
+                   EfiACPIMemoryNVS,
+                   EFI_SIZE_TO_PAGES (sizeof (DEBUG_AGENT_MAILBOX) + PcdGet16 (PcdDebugPortHandleBufferSize)),
+                   &Address
+                   );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "DebugAgent: Cannot install configuration table for mailbox!\n"));
+    CpuDeadLoop ();
+  }
+
+  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);
+
+  NewMailbox = (DEBUG_AGENT_MAILBOX *)(UINTN)Address;
+  //
+  // Copy Mailbox and Debug Port Handle buffer to new location in ACPI NVS memory, because original Mailbox
+  // and Debug Port Handle buffer may be free at runtime, SMM debug agent needs to access them
+  //
+  Mailbox = GetMailboxPointer ();
+  CopyMem (NewMailbox, Mailbox, sizeof (DEBUG_AGENT_MAILBOX));
+  CopyMem (NewMailbox + 1, (VOID *)(UINTN)Mailbox->DebugPortHandle, PcdGet16 (PcdDebugPortHandleBufferSize));
+  //
+  // Update Debug Port Handle in new Mailbox
+  //
+  UpdateMailboxContent (NewMailbox, DEBUG_MAILBOX_DEBUG_PORT_HANDLE_INDEX, (UINT64)(UINTN)(NewMailbox + 1));
+  mMailboxPointer = NewMailbox;
+
+  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);
+
+  Status = gBS->InstallConfigurationTable (&gEfiDebugAgentGuid, (VOID *)mMailboxPointer);
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "DebugAgent: Failed to install configuration for mailbox!\n"));
+    CpuDeadLoop ();
+  }
+}
+
+/**
+  Debug Agent constructor function.
+
+  @param[in]  ImageHandle   The firmware allocated handle for the EFI image.
+  @param[in]  SystemTable   A pointer to the EFI System Table.
+
+  @retval  RETURN_SUCCESS  When this function completed.
+
+**/
+RETURN_STATUS
+EFIAPI
+DxeDebugAgentLibConstructor (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  if (mDxeCoreFlag) {
+    //
+    // Invoke internal constructor function only when DXE core links this library instance
+    //
+    InternalConstructorWorker ();
+  }
+
+  return RETURN_SUCCESS;
+}
+
+/**
+  Get the pointer to Mailbox from the configuration table.
+
+  @return Pointer to Mailbox.
+
+**/
+DEBUG_AGENT_MAILBOX *
+GetMailboxFromConfigurationTable (
+  VOID
+  )
+{
+  EFI_STATUS           Status;
+  DEBUG_AGENT_MAILBOX  *Mailbox;
+
+  Status = EfiGetSystemConfigurationTable (&gEfiDebugAgentGuid, (VOID **)&Mailbox);
+  if ((Status == EFI_SUCCESS) && (Mailbox != NULL)) {
+    VerifyMailboxChecksum (Mailbox);
+    return Mailbox;
+  } else {
+    return NULL;
+  }
+}
+
+/**
+  Get the pointer to Mailbox from the GUIDed HOB.
+
+  @param[in]  HobStart      The starting HOB pointer to search from.
+
+  @return Pointer to Mailbox.
+
+**/
+DEBUG_AGENT_MAILBOX *
+GetMailboxFromHob (
+  IN VOID  *HobStart
+  )
+{
+  EFI_HOB_GUID_TYPE    *GuidHob;
+  UINT64               *MailboxLocation;
+  DEBUG_AGENT_MAILBOX  *Mailbox;
+
+  GuidHob = GetNextGuidHob (&gEfiDebugAgentGuid, HobStart);
+  if (GuidHob == NULL) {
+    return NULL;
+  }
+
+  MailboxLocation = (UINT64 *)(GET_GUID_HOB_DATA (GuidHob));
+  Mailbox         = (DEBUG_AGENT_MAILBOX *)(UINTN)(*MailboxLocation);
+  VerifyMailboxChecksum (Mailbox);
+
+  return Mailbox;
+}
+
+/**
+  Get Debug Agent Mailbox pointer.
+
+  @return Mailbox pointer.
+
+**/
+DEBUG_AGENT_MAILBOX *
+GetMailboxPointer (
+  VOID
+  )
+{
+  AcquireMpSpinLock (&mDebugMpContext.MailboxSpinLock);
+  VerifyMailboxChecksum (mMailboxPointer);
+  ReleaseMpSpinLock (&mDebugMpContext.MailboxSpinLock);
+  return mMailboxPointer;
+}
+
+/**
+  Get debug port handle.
+
+  @return Debug port handle.
+
+**/
+DEBUG_PORT_HANDLE
+GetDebugPortHandle (
+  VOID
+  )
+{
+  return (DEBUG_PORT_HANDLE)(UINTN)(GetMailboxPointer ()->DebugPortHandle);
+}
+
+/**
+  Worker function to set up Debug Agent environment.
+
+  This function will set up IDT table and initialize the IDT entries and
+  initialize CPU LOCAL APIC timer.
+  It also tries to connect HOST if Debug Agent was not initialized before.
+
+  @param[in] Mailbox        Pointer to Mailbox.
+
+**/
+VOID
+SetupDebugAgentEnvironment (
+  IN DEBUG_AGENT_MAILBOX  *Mailbox
+  )
+{
+  IA32_DESCRIPTOR  Idtr;
+  UINT16           IdtEntryCount;
+  UINT64           DebugPortHandle;
+  UINT32           DebugTimerFrequency;
+
+  if (mMultiProcessorDebugSupport) {
+    InitializeSpinLock (&mDebugMpContext.MpContextSpinLock);
+    InitializeSpinLock (&mDebugMpContext.DebugPortSpinLock);
+    InitializeSpinLock (&mDebugMpContext.MailboxSpinLock);
+    //
+    // Clear Break CPU index value
+    //
+    mDebugMpContext.BreakAtCpuIndex = (UINT32)-1;
+  }
+
+  //
+  // Get original IDT address and size.
+  //
+  AsmReadIdtr ((IA32_DESCRIPTOR *)&Idtr);
+  IdtEntryCount = (UINT16)((Idtr.Limit + 1) / sizeof (IA32_IDT_GATE_DESCRIPTOR));
+  if (IdtEntryCount < 33) {
+    ZeroMem (&mIdtEntryTable, sizeof (IA32_IDT_GATE_DESCRIPTOR) * 33);
+    //
+    // Copy original IDT table into new one
+    //
+    CopyMem (&mIdtEntryTable, (VOID *)Idtr.Base, Idtr.Limit + 1);
+    //
+    // Load new IDT table
+    //
+    Idtr.Limit = (UINT16)(sizeof (IA32_IDT_GATE_DESCRIPTOR) * 33 - 1);
+    Idtr.Base  = (UINTN)&mIdtEntryTable;
+    AsmWriteIdtr ((IA32_DESCRIPTOR *)&Idtr);
+  }
+
+  //
+  // Initialize the IDT table entries to support source level debug.
+  //
+  InitializeDebugIdt ();
+
+  //
+  // If mMailboxPointer is not set before, set it
+  //
+  if (mMailboxPointer == NULL) {
+    if (Mailbox != NULL) {
+      //
+      // If Mailbox exists, copy it into one global variable
+      //
+      CopyMem (&mMailbox, Mailbox, sizeof (DEBUG_AGENT_MAILBOX));
+    } else {
+      ZeroMem (&mMailbox, sizeof (DEBUG_AGENT_MAILBOX));
+    }
+
+    mMailboxPointer = &mMailbox;
+  }
+
+  //
+  // Initialize Debug Timer hardware and save its initial count and frequency
+  //
+  mDebugMpContext.DebugTimerInitCount = InitializeDebugTimer (&DebugTimerFrequency, TRUE);
+  UpdateMailboxContent (mMailboxPointer, DEBUG_MAILBOX_DEBUG_TIMER_FREQUENCY, DebugTimerFrequency);
+  //
+  // Initialize debug communication port
+  //
+  DebugPortHandle = (UINT64)(UINTN)DebugPortInitialize ((VOID *)(UINTN)mMailboxPointer->DebugPortHandle, NULL);
+  UpdateMailboxContent (mMailboxPointer, DEBUG_MAILBOX_DEBUG_PORT_HANDLE_INDEX, DebugPortHandle);
+
+  if (Mailbox == NULL) {
+    //
+    // Trigger one software interrupt to inform HOST
+    //
+    TriggerSoftInterrupt (SYSTEM_RESET_SIGNATURE);
+    SetDebugFlag (DEBUG_AGENT_FLAG_MEMORY_READY, 1);
+    //
+    // Memory has been ready
+    //
+    if (IsHostAttached ()) {
+      //
+      // Trigger one software interrupt to inform HOST
+      //
+      TriggerSoftInterrupt (MEMORY_READY_SIGNATURE);
+    }
+  }
+}
+
+/**
+  Initialize debug agent.
+
+  This function is used to set up debug environment for DXE phase.
+
+  If this function is called by DXE Core, Context must be the pointer
+  to HOB list which will be used to get GUIDed HOB. It will enable
+  interrupt to support break-in feature.
+  If this function is called by DXE module, Context must be NULL. It
+  will enable interrupt to support break-in feature.
+
+  @param[in] InitFlag     Init flag is used to decide initialize process.
+  @param[in] Context      Context needed according to InitFlag.
+  @param[in] Function     Continue function called by debug agent library; it was
+                          optional.
+
+**/
+VOID
+EFIAPI
+InitializeDebugAgent (
+  IN UINT32                InitFlag,
+  IN VOID                  *Context  OPTIONAL,
+  IN DEBUG_AGENT_CONTINUE  Function  OPTIONAL
+  )
+{
+  UINT64               *MailboxLocation;
+  DEBUG_AGENT_MAILBOX  *Mailbox;
+  BOOLEAN              InterruptStatus;
+  VOID                 *HobList;
+  IA32_DESCRIPTOR      IdtDescriptor;
+  IA32_DESCRIPTOR      *Ia32Idtr;
+  IA32_IDT_ENTRY       *Ia32IdtEntry;
+  BOOLEAN              PeriodicMode;
+  UINTN                TimerCycle;
+
+  if (InitFlag == DEBUG_AGENT_INIT_DXE_AP) {
+    //
+    // Check if CPU APIC Timer is working, otherwise initialize it.
+    //
+    InitializeLocalApicSoftwareEnable (TRUE);
+    GetApicTimerState (NULL, &PeriodicMode, NULL);
+    TimerCycle = GetApicTimerInitCount ();
+    if (!PeriodicMode || (TimerCycle == 0)) {
+      InitializeDebugTimer (NULL, FALSE);
+    }
+
+    //
+    // Invoked by AP, enable interrupt to let AP could receive IPI from other processors
+    //
+    EnableInterrupts ();
+    return;
+  }
+
+  //
+  // Disable Debug Timer interrupt
+  //
+  SaveAndSetDebugTimerInterrupt (FALSE);
+  //
+  // Save and disable original interrupt status
+  //
+  InterruptStatus = SaveAndDisableInterrupts ();
+
+  //
+  // Try to get mailbox firstly
+  //
+  HobList         = NULL;
+  Mailbox         = NULL;
+  MailboxLocation = NULL;
+
+  switch (InitFlag) {
+    case DEBUG_AGENT_INIT_DXE_LOAD:
+      //
+      // Check if Debug Agent has been initialized before
+      //
+      if (IsDebugAgentInitialzed ()) {
+        DEBUG ((DEBUG_INFO, "Debug Agent: The former agent will be overwritten by the new one!\n"));
+      }
+
+      mMultiProcessorDebugSupport = TRUE;
+      //
+      // Save original IDT table
+      //
+      AsmReadIdtr (&IdtDescriptor);
+      mSaveIdtTableSize = IdtDescriptor.Limit + 1;
+      mSavedIdtTable    = AllocateCopyPool (mSaveIdtTableSize, (VOID *)IdtDescriptor.Base);
+      //
+      // Check if Debug Agent initialized in DXE phase
+      //
+      Mailbox = GetMailboxFromConfigurationTable ();
+      if (Mailbox == NULL) {
+        //
+        // Try to get mailbox from GUIDed HOB build in PEI
+        //
+        HobList = GetHobList ();
+        Mailbox = GetMailboxFromHob (HobList);
+      }
+
+      //
+      // Set up Debug Agent Environment and try to connect HOST if required
+      //
+      SetupDebugAgentEnvironment (Mailbox);
+      //
+      // For DEBUG_AGENT_INIT_S3, needn't to install configuration table and EFI Serial IO protocol
+      // For DEBUG_AGENT_INIT_DXE_CORE, InternalConstructorWorker() will invoked in Constructor()
+      //
+      InternalConstructorWorker ();
+      //
+      // Enable Debug Timer interrupt
+      //
+      SaveAndSetDebugTimerInterrupt (TRUE);
+      //
+      // Enable interrupt to receive Debug Timer interrupt
+      //
+      EnableInterrupts ();
+
+      mDebugAgentInitialized = TRUE;
+      FindAndReportModuleImageInfo (SIZE_4KB);
+
+      *(EFI_STATUS *)Context = EFI_SUCCESS;
+
+      break;
+
+    case DEBUG_AGENT_INIT_DXE_UNLOAD:
+      if (mDebugAgentInitialized) {
+        if (IsHostAttached ()) {
+          *(EFI_STATUS *)Context = EFI_ACCESS_DENIED;
+          //
+          // Enable Debug Timer interrupt again
+          //
+          SaveAndSetDebugTimerInterrupt (TRUE);
+        } else {
+          //
+          // Restore original IDT table
+          //
+          AsmReadIdtr (&IdtDescriptor);
+          IdtDescriptor.Limit = (UINT16)(mSaveIdtTableSize - 1);
+          CopyMem ((VOID *)IdtDescriptor.Base, mSavedIdtTable, mSaveIdtTableSize);
+          AsmWriteIdtr (&IdtDescriptor);
+          FreePool (mSavedIdtTable);
+          mDebugAgentInitialized = FALSE;
+          *(EFI_STATUS *)Context = EFI_SUCCESS;
+        }
+      } else {
+        *(EFI_STATUS *)Context = EFI_NOT_STARTED;
+      }
+
+      //
+      // Restore interrupt state.
+      //
+      SetInterruptState (InterruptStatus);
+      break;
+
+    case DEBUG_AGENT_INIT_DXE_CORE:
+      mDxeCoreFlag                = TRUE;
+      mMultiProcessorDebugSupport = TRUE;
+      //
+      // Try to get mailbox from GUIDed HOB build in PEI
+      //
+      HobList = Context;
+      Mailbox = GetMailboxFromHob (HobList);
+      //
+      // Set up Debug Agent Environment and try to connect HOST if required
+      //
+      SetupDebugAgentEnvironment (Mailbox);
+      //
+      // Enable Debug Timer interrupt
+      //
+      SaveAndSetDebugTimerInterrupt (TRUE);
+      //
+      // Enable interrupt to receive Debug Timer interrupt
+      //
+      EnableInterrupts ();
+
+      break;
+
+    case DEBUG_AGENT_INIT_S3:
+
+      if (Context != NULL) {
+        Ia32Idtr        =  (IA32_DESCRIPTOR *)Context;
+        Ia32IdtEntry    = (IA32_IDT_ENTRY *)(Ia32Idtr->Base);
+        MailboxLocation = (UINT64 *)((UINTN)Ia32IdtEntry[DEBUG_MAILBOX_VECTOR].Bits.OffsetLow +
+                                     ((UINTN)Ia32IdtEntry[DEBUG_MAILBOX_VECTOR].Bits.OffsetHigh << 16));
+        Mailbox = (DEBUG_AGENT_MAILBOX *)(UINTN)(*MailboxLocation);
+        VerifyMailboxChecksum (Mailbox);
+      }
+
+      //
+      // Save Mailbox pointer in global variable
+      //
+      mMailboxPointer = Mailbox;
+      //
+      // Set up Debug Agent Environment and try to connect HOST if required
+      //
+      SetupDebugAgentEnvironment (Mailbox);
+      //
+      // Disable interrupt
+      //
+      DisableInterrupts ();
+      FindAndReportModuleImageInfo (SIZE_4KB);
+      if (GetDebugFlag (DEBUG_AGENT_FLAG_BREAK_BOOT_SCRIPT) == 1) {
+        //
+        // If Boot Script entry break is set, code will be break at here.
+        //
+        CpuBreakpoint ();
+      }
+
+      break;
+
+    default:
+      //
+      // Only DEBUG_AGENT_INIT_PREMEM_SEC and DEBUG_AGENT_INIT_POSTMEM_SEC are allowed for this
+      // Debug Agent library instance.
+      //
+      DEBUG ((DEBUG_ERROR, "Debug Agent: The InitFlag value is not allowed!\n"));
+      CpuDeadLoop ();
+      break;
+  }
+}
diff --git a/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/DxeDebugAgentLib.h b/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/DxeDebugAgentLib.h
index bd178db3e1..8d1d917a6a 100644
--- a/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/DxeDebugAgentLib.h
+++ b/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/DxeDebugAgentLib.h
@@ -1,34 +1,34 @@
-/** @file

-  Header file for Dxe Core Debug Agent Library instance.

-

-  Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>

-  SPDX-License-Identifier: BSD-2-Clause-Patent

-

-**/

-

-#ifndef _DXE_CORE_DEBUG_AGENT_LIB_H_

-#define _DXE_CORE_DEBUG_AGENT_LIB_H_

-

-#include <PiDxe.h>

-

-#include <Protocol/SerialIo.h>

-#include <Protocol/DevicePath.h>

-#include <Protocol/PiPcd.h>

-

-#include <Library/UefiBootServicesTableLib.h>

-#include <Library/UefiLib.h>

-#include <Library/DevicePathLib.h>

-#include <Library/MemoryAllocationLib.h>

-

-#include "DebugAgent.h"

-

-/**

-  Install EFI Serial IO protocol based on Debug Communication Library.

-

-**/

-VOID

-InstallSerialIo (

-  VOID

-  );

-

-#endif

+/** @file
+  Header file for Dxe Core Debug Agent Library instance.
+
+  Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef _DXE_CORE_DEBUG_AGENT_LIB_H_
+#define _DXE_CORE_DEBUG_AGENT_LIB_H_
+
+#include <PiDxe.h>
+
+#include <Protocol/SerialIo.h>
+#include <Protocol/DevicePath.h>
+#include <Protocol/PiPcd.h>
+
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+#include <Library/DevicePathLib.h>
+#include <Library/MemoryAllocationLib.h>
+
+#include "DebugAgent.h"
+
+/**
+  Install EFI Serial IO protocol based on Debug Communication Library.
+
+**/
+VOID
+InstallSerialIo (
+  VOID
+  );
+
+#endif
diff --git a/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/SerialIo.c b/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/SerialIo.c
index 97d30c802d..51ae757d2b 100644
--- a/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/SerialIo.c
+++ b/SourceLevelDebugPkg/Library/DebugAgent/DxeDebugAgent/SerialIo.c
@@ -1,827 +1,827 @@
-/** @file

-  Install Serial IO Protocol that layers on top of a Debug Communication Library instance.

-

-  Copyright (c) 2012 - 2018, Intel Corporation. All rights reserved.<BR>

-  SPDX-License-Identifier: BSD-2-Clause-Patent

-

-**/

-

-#include "DxeDebugAgentLib.h"

-

-//

-// Serial I/O Protocol Interface definitions.

-//

-

-/**

-  Reset serial device.

-

-  @param[in] This           Pointer to EFI_SERIAL_IO_PROTOCOL.

-

-  @retval EFI_SUCCESS       Reset successfully.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialReset (

-  IN EFI_SERIAL_IO_PROTOCOL  *This

-  );

-

-/**

-  Set new attributes to a serial device.

-

-  @param[in]  This                Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[in]  BaudRate            The baudrate of the serial device.

-  @param[in]  ReceiveFifoDepth    The depth of receive FIFO buffer.

-  @param[in]  Timeout             The request timeout for a single char.

-  @param[in]  Parity              The type of parity used in serial device.

-  @param[in]  DataBits            Number of databits used in serial device.

-  @param[in]  StopBits            Number of stopbits used in serial device.

-

-  @retval EFI_SUCCESS             The new attributes were set.

-  @retval EFI_INVALID_PARAMETER   One or more attributes have an unsupported value.

-  @retval EFI_DEVICE_ERROR        The serial device is not functioning correctly (no return).

-

-**/

-EFI_STATUS

-EFIAPI

-SerialSetAttributes (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  IN UINT64                  BaudRate,

-  IN UINT32                  ReceiveFifoDepth,

-  IN UINT32                  Timeout,

-  IN EFI_PARITY_TYPE         Parity,

-  IN UINT8                   DataBits,

-  IN EFI_STOP_BITS_TYPE      StopBits

-  );

-

-/**

-  Set Control Bits.

-

-  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[in] Control         Control bits that can be settable.

-

-  @retval EFI_SUCCESS        New Control bits were set successfully.

-  @retval EFI_UNSUPPORTED    The Control bits wanted to set are not supported.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialSetControl (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  IN UINT32                  Control

-  );

-

-/**

-  Get ControlBits.

-

-  @param[in]  This         Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[out] Control      Control signals of the serial device.

-

-  @retval EFI_SUCCESS  Get Control signals successfully.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialGetControl (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  OUT UINT32                 *Control

-  );

-

-/**

-  Write the specified number of bytes to serial device.

-

-  @param[in]      This       Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[in, out] BufferSize On input the size of Buffer, on output the amount of

-                             data actually written.

-  @param[in]      Buffer     The buffer of data to write.

-

-  @retval EFI_SUCCESS        The data were written successfully.

-  @retval EFI_DEVICE_ERROR   The device reported an error.

-  @retval EFI_TIMEOUT        The write operation was stopped due to timeout.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialWrite (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  IN OUT UINTN               *BufferSize,

-  IN VOID                    *Buffer

-  );

-

-/**

-  Read the specified number of bytes from serial device.

-

-  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[in, out] BufferSize On input the size of Buffer, on output the amount of

-                             data returned in buffer.

-  @param[out] Buffer         The buffer to return the data into.

-

-  @retval EFI_SUCCESS        The data were read successfully.

-  @retval EFI_DEVICE_ERROR   The device reported an error.

-  @retval EFI_TIMEOUT        The read operation was stopped due to timeout.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialRead (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  IN OUT UINTN               *BufferSize,

-  OUT VOID                   *Buffer

-  );

-

-//

-// Serial Driver Defaults

-//

-#define SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH  1

-#define SERIAL_PORT_DEFAULT_TIMEOUT             1000000

-#define SERIAL_PORT_DEFAULT_CONTROL_MASK        0

-#define SERIAL_PORT_LOOPBACK_BUFFER_FULL        BIT8

-

-//

-// EFI_SERIAL_IO_MODE instance

-//

-EFI_SERIAL_IO_MODE  mSerialIoMode = {

-  SERIAL_PORT_DEFAULT_CONTROL_MASK,

-  SERIAL_PORT_DEFAULT_TIMEOUT,

-  0,  // default BaudRate

-  SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH,

-  0,  // default DataBits

-  0,  // default Parity

-  0   // default StopBits

-};

-

-//

-// EFI_SERIAL_IO_PROTOCOL instance

-//

-EFI_SERIAL_IO_PROTOCOL  mSerialIo = {

-  SERIAL_IO_INTERFACE_REVISION,

-  SerialReset,

-  SerialSetAttributes,

-  SerialSetControl,

-  SerialGetControl,

-  SerialWrite,

-  SerialRead,

-  &mSerialIoMode

-};

-

-//

-// Serial IO Device Path definition

-//

-typedef struct {

-  VENDOR_DEVICE_PATH          VendorDevicePath;

-  UART_DEVICE_PATH            UartDevicePath;

-  EFI_DEVICE_PATH_PROTOCOL    EndDevicePath;

-} SERIAL_IO_DEVICE_PATH;

-

-//

-// Serial IO Device Patch instance

-//

-SERIAL_IO_DEVICE_PATH  mSerialIoDevicePath = {

-  {

-    {

-      HARDWARE_DEVICE_PATH,

-      HW_VENDOR_DP,

-      {

-        (UINT8)(sizeof (VENDOR_DEVICE_PATH)),

-        (UINT8)((sizeof (VENDOR_DEVICE_PATH)) >> 8)

-      }

-    },

-    EFI_DEBUG_AGENT_GUID,

-  },

-  {

-    {

-      MESSAGING_DEVICE_PATH,

-      MSG_UART_DP,

-      {

-        (UINT8)(sizeof (UART_DEVICE_PATH)),

-        (UINT8)((sizeof (UART_DEVICE_PATH)) >> 8)

-      }

-    },

-    0,

-    0,  // default BaudRate

-    0,  // default DataBits

-    0,  // default Parity

-    0,  // default StopBits

-  },

-  {

-    END_DEVICE_PATH_TYPE,

-    END_ENTIRE_DEVICE_PATH_SUBTYPE,

-    {

-      END_DEVICE_PATH_LENGTH,

-      0

-    }

-  }

-};

-

-#define DEBUG_SERIAL_IO_FIFO_DEPTH  10

-//

-//  Data buffer for Terminal input character and Debug Symbols.

-//  The depth is DEBUG_SERIAL_IO_FIFO_DEPTH.

-//  Fields:

-//      First   UINT8: The index of the first data in array Data[].

-//      Last    UINT8: The index, which you can put a new data into array Data[].

-//      Surplus UINT8: Identify how many data you can put into array Data[].

-//      Data[]  UINT8: An array, which used to store data.

-//

-typedef struct {

-  UINT8    First;

-  UINT8    Last;

-  UINT8    Surplus;

-  UINT8    Data[DEBUG_SERIAL_IO_FIFO_DEPTH];

-} DEBUG_SERIAL_FIFO;

-

-//

-// Global Variables

-//

-EFI_HANDLE         mSerialIoHandle        = NULL;

-UINTN              mLoopbackBuffer        = 0;

-DEBUG_SERIAL_FIFO  mSerialFifoForTerminal = {

-  0, 0, DEBUG_SERIAL_IO_FIFO_DEPTH, { 0 }

-};

-DEBUG_SERIAL_FIFO  mSerialFifoForDebug = {

-  0, 0, DEBUG_SERIAL_IO_FIFO_DEPTH, { 0 }

-};

-

-/**

-  Detect whether specific FIFO is empty or not.

-

-  @param[in]  Fifo    A pointer to the Data Structure DEBUG_SERIAL_FIFO.

-

-  @return whether specific FIFO is empty or not.

-

-**/

-BOOLEAN

-IsDebugTerminalFifoEmpty (

-  IN DEBUG_SERIAL_FIFO  *Fifo

-  )

-{

-  if (Fifo->Surplus == DEBUG_SERIAL_IO_FIFO_DEPTH) {

-    return TRUE;

-  }

-

-  return FALSE;

-}

-

-/**

-  Detect whether specific FIFO is full or not.

-

-  @param[in] Fifo    A pointer to the Data Structure DEBUG_SERIAL_FIFO.

-

-  @return whether specific FIFO is full or not.

-

-**/

-BOOLEAN

-IsDebugTerminalFifoFull (

-  IN DEBUG_SERIAL_FIFO  *Fifo

-  )

-

-{

-  if (Fifo->Surplus == 0) {

-    return TRUE;

-  }

-

-  return FALSE;

-}

-

-/**

-  Add data to specific FIFO.

-

-  @param[in] Fifo               A pointer to the Data Structure DEBUG_SERIAL_FIFO.

-  @param[in] Data               The data added to FIFO.

-

-  @retval EFI_SUCCESS           Add data to specific FIFO successfully.

-  @retval EFI_OUT_OF_RESOURCE   Failed to add data because FIFO is already full.

-

-**/

-EFI_STATUS

-DebugTerminalFifoAdd (

-  IN DEBUG_SERIAL_FIFO  *Fifo,

-  IN UINT8              Data

-  )

-

-{

-  //

-  // if FIFO full can not add data

-  //

-  if (IsDebugTerminalFifoFull (Fifo)) {

-    return EFI_OUT_OF_RESOURCES;

-  }

-

-  //

-  // FIFO is not full can add data

-  //

-  Fifo->Data[Fifo->Last] = Data;

-  Fifo->Surplus--;

-  Fifo->Last++;

-  if (Fifo->Last == DEBUG_SERIAL_IO_FIFO_DEPTH) {

-    Fifo->Last = 0;

-  }

-

-  return EFI_SUCCESS;

-}

-

-/**

-  Remove data from specific FIFO.

-

-  @param[in]  Fifo              A pointer to the Data Structure DEBUG_SERIAL_FIFO.

-  @param[out] Data              The data removed from FIFO.

-

-  @retval EFI_SUCCESS           Remove data from specific FIFO successfully.

-  @retval EFI_OUT_OF_RESOURCE   Failed to remove data because FIFO is empty.

-

-**/

-EFI_STATUS

-DebugTerminalFifoRemove (

-  IN  DEBUG_SERIAL_FIFO  *Fifo,

-  OUT UINT8              *Data

-  )

-{

-  //

-  // if FIFO is empty, no data can remove

-  //

-  if (IsDebugTerminalFifoEmpty (Fifo)) {

-    return EFI_OUT_OF_RESOURCES;

-  }

-

-  //

-  // FIFO is not empty, can remove data

-  //

-  *Data = Fifo->Data[Fifo->First];

-  Fifo->Surplus++;

-  Fifo->First++;

-  if (Fifo->First == DEBUG_SERIAL_IO_FIFO_DEPTH) {

-    Fifo->First = 0;

-  }

-

-  return EFI_SUCCESS;

-}

-

-/**

-  Install EFI Serial IO protocol based on Debug Communication Library.

-

-**/

-VOID

-InstallSerialIo (

-  VOID

-  )

-{

-  EFI_STATUS  Status;

-

-  Status = gBS->InstallMultipleProtocolInterfaces (

-                  &mSerialIoHandle,

-                  &gEfiDevicePathProtocolGuid,

-                  &mSerialIoDevicePath,

-                  &gEfiSerialIoProtocolGuid,

-                  &mSerialIo,

-                  NULL

-                  );

-  if (EFI_ERROR (Status)) {

-    DEBUG ((DEBUG_ERROR, "Debug Agent: Failed to install EFI Serial IO Protocol on Debug Port!\n"));

-  }

-}

-

-/**

-  Reset serial device.

-

-  @param[in] This           Pointer to EFI_SERIAL_IO_PROTOCOL.

-

-  @retval EFI_SUCCESS       Reset successfully.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialReset (

-  IN EFI_SERIAL_IO_PROTOCOL  *This

-  )

-{

-  mSerialIoMode.ControlMask = SERIAL_PORT_DEFAULT_CONTROL_MASK;

-  mLoopbackBuffer           = 0;

-  //

-  // Not reset serial device hardware indeed.

-  //

-  return EFI_SUCCESS;

-}

-

-/**

-  Set new attributes to a serial device.

-

-  @param[in]  This                Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[in]  BaudRate            The baudrate of the serial device.

-  @param[in]  ReceiveFifoDepth    The depth of receive FIFO buffer.

-  @param[in]  Timeout             The request timeout for a single char.

-  @param[in]  Parity              The type of parity used in serial device.

-  @param[in]  DataBits            Number of databits used in serial device.

-  @param[in]  StopBits            Number of stopbits used in serial device.

-

-  @retval EFI_SUCCESS             The new attributes were set.

-  @retval EFI_INVALID_PARAMETER   One or more attributes have an unsupported value.

-  @retval EFI_DEVICE_ERROR        The serial device is not functioning correctly (no return).

-

-**/

-EFI_STATUS

-EFIAPI

-SerialSetAttributes (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  IN UINT64                  BaudRate,

-  IN UINT32                  ReceiveFifoDepth,

-  IN UINT32                  Timeout,

-  IN EFI_PARITY_TYPE         Parity,

-  IN UINT8                   DataBits,

-  IN EFI_STOP_BITS_TYPE      StopBits

-  )

-{

-  //

-  // The Debug Communication Library CAN NOT change communications parameters (if it has)

-  // actually. Because it also has no any idea on what parameters are based on, we cannot

-  // check the input parameters (like BaudRate, Parity, DataBits and StopBits).

-  //

-

-  //

-  // Update the Timeout value in the mode structure based on the request.

-  // The Debug Communication Library can not support a timeout on writes, but the timeout on

-  // reads can be provided by this module.

-  //

-  if (Timeout == 0) {

-    mSerialIoMode.Timeout = SERIAL_PORT_DEFAULT_TIMEOUT;

-  } else {

-    mSerialIoMode.Timeout = Timeout;

-  }

-

-  //

-  // Update the ReceiveFifoDepth value in the mode structure based on the request.

-  // This module assumes that the Debug Communication Library uses a FIFO depth of

-  // SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH.  The Debug Communication Library may actually be

-  // using a larger FIFO, but there is no way to tell.

-  //

-  if ((ReceiveFifoDepth == 0) || (ReceiveFifoDepth >= SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH)) {

-    mSerialIoMode.ReceiveFifoDepth = SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH;

-  } else {

-    return EFI_INVALID_PARAMETER;

-  }

-

-  return EFI_SUCCESS;

-}

-

-/**

-  Set Control Bits.

-

-  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[in] Control         Control bits that can be settable.

-

-  @retval EFI_SUCCESS        New Control bits were set successfully.

-  @retval EFI_UNSUPPORTED    The Control bits wanted to set are not supported.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialSetControl (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  IN UINT32                  Control

-  )

-{

-  //

-  // The only control bit supported by this module is software loopback.

-  // If any other bit is set, then return an error

-  //

-  if ((Control & (~EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE)) != 0) {

-    return EFI_UNSUPPORTED;

-  }

-

-  mSerialIoMode.ControlMask = Control;

-  return EFI_SUCCESS;

-}

-

-/**

-  Get ControlBits.

-

-  @param[in]  This         Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[out] Control      Control signals of the serial device.

-

-  @retval EFI_SUCCESS  Get Control signals successfully.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialGetControl (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  OUT UINT32                 *Control

-  )

-{

-  DEBUG_PORT_HANDLE  Handle;

-  BOOLEAN            DebugTimerInterruptState;

-  EFI_TPL            Tpl;

-

-  //

-  // Raise TPL to prevent recursion from EFI timer interrupts

-  //

-  Tpl = gBS->RaiseTPL (TPL_NOTIFY);

-

-  //

-  // Save and disable Debug Timer interrupt to avoid it to access Debug Port

-  //

-  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);

-  Handle                   = GetDebugPortHandle ();

-

-  //

-  // Always assume the output buffer is empty and the Debug Communication Library can process

-  // more write requests.

-  //

-  *Control = mSerialIoMode.ControlMask | EFI_SERIAL_OUTPUT_BUFFER_EMPTY;

-

-  //

-  // Check to see if the Terminal FIFO is empty and

-  // check to see if the input buffer in the Debug Communication Library is empty

-  //

-  if (!IsDebugTerminalFifoEmpty (&mSerialFifoForTerminal) || DebugPortPollBuffer (Handle)) {

-    *Control &= ~EFI_SERIAL_INPUT_BUFFER_EMPTY;

-  }

-

-  //

-  // Restore Debug Timer interrupt

-  //

-  SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);

-

-  //

-  // Restore to original TPL

-  //

-  gBS->RestoreTPL (Tpl);

-

-  return EFI_SUCCESS;

-}

-

-/**

-  Write the specified number of bytes to serial device.

-

-  @param[in]      This       Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[in, out] BufferSize On input the size of Buffer, on output the amount of

-                             data actually written.

-  @param[in]      Buffer     The buffer of data to write.

-

-  @retval EFI_SUCCESS        The data were written successfully.

-  @retval EFI_DEVICE_ERROR   The device reported an error.

-  @retval EFI_TIMEOUT        The write operation was stopped due to timeout.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialWrite (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  IN OUT UINTN               *BufferSize,

-  IN VOID                    *Buffer

-  )

-{

-  DEBUG_PORT_HANDLE  Handle;

-  BOOLEAN            DebugTimerInterruptState;

-  EFI_TPL            Tpl;

-

-  //

-  // Raise TPL to prevent recursion from EFI timer interrupts

-  //

-  Tpl = gBS->RaiseTPL (TPL_NOTIFY);

-

-  //

-  // Save and disable Debug Timer interrupt to avoid it to access Debug Port

-  //

-  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);

-  Handle                   = GetDebugPortHandle ();

-

-  if ((mSerialIoMode.ControlMask & EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE) != 0) {

-    if (*BufferSize == 0) {

-      return EFI_SUCCESS;

-    }

-

-    if ((mLoopbackBuffer & SERIAL_PORT_LOOPBACK_BUFFER_FULL) != 0) {

-      *BufferSize = 0;

-      return EFI_TIMEOUT;

-    }

-

-    mLoopbackBuffer = SERIAL_PORT_LOOPBACK_BUFFER_FULL | *(UINT8 *)Buffer;

-    *BufferSize     = 1;

-  } else {

-    *BufferSize = DebugPortWriteBuffer (Handle, Buffer, *BufferSize);

-  }

-

-  //

-  // Restore Debug Timer interrupt

-  //

-  SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);

-

-  //

-  // Restore to original TPL

-  //

-  gBS->RestoreTPL (Tpl);

-

-  return EFI_SUCCESS;

-}

-

-/**

-  Read the specified number of bytes from serial device.

-

-  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.

-  @param[in, out] BufferSize On input the size of Buffer, on output the amount of

-                             data returned in buffer.

-  @param[out] Buffer         The buffer to return the data into.

-

-  @retval EFI_SUCCESS        The data were read successfully.

-  @retval EFI_DEVICE_ERROR   The device reported an error.

-  @retval EFI_TIMEOUT        The read operation was stopped due to timeout.

-

-**/

-EFI_STATUS

-EFIAPI

-SerialRead (

-  IN EFI_SERIAL_IO_PROTOCOL  *This,

-  IN OUT UINTN               *BufferSize,

-  OUT VOID                   *Buffer

-  )

-{

-  EFI_STATUS           Status;

-  UINTN                Index;

-  UINT8                *Uint8Buffer;

-  BOOLEAN              DebugTimerInterruptState;

-  EFI_TPL              Tpl;

-  DEBUG_PORT_HANDLE    Handle;

-  DEBUG_PACKET_HEADER  DebugHeader;

-  UINT8                *Data8;

-

-  //

-  // Raise TPL to prevent recursion from EFI timer interrupts

-  //

-  Tpl = gBS->RaiseTPL (TPL_NOTIFY);

-

-  //

-  // Save and disable Debug Timer interrupt to avoid it to access Debug Port

-  //

-  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);

-  Handle                   = GetDebugPortHandle ();

-

-  Data8       = (UINT8 *)&DebugHeader;

-  Uint8Buffer = (UINT8 *)Buffer;

-  if ((mSerialIoMode.ControlMask & EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE) != 0) {

-    if ((mLoopbackBuffer & SERIAL_PORT_LOOPBACK_BUFFER_FULL) == 0) {

-      return EFI_TIMEOUT;

-    }

-

-    *Uint8Buffer    = (UINT8)(mLoopbackBuffer & 0xff);

-    mLoopbackBuffer = 0;

-    *BufferSize     = 1;

-  } else {

-    for (Index = 0; Index < *BufferSize; Index++) {

-      //

-      // Read input character from terminal FIFO firstly

-      //

-      Status = DebugTerminalFifoRemove (&mSerialFifoForTerminal, Data8);

-      if (Status == EFI_SUCCESS) {

-        *Uint8Buffer = *Data8;

-        Uint8Buffer++;

-        continue;

-      }

-

-      //

-      // Read the input character from Debug Port

-      //

-      if (!DebugPortPollBuffer (Handle)) {

-        break;

-      }

-

-      DebugAgentReadBuffer (Handle, Data8, 1, 0);

-

-      if (*Data8 == DEBUG_STARTING_SYMBOL_ATTACH) {

-        //

-        // Add the debug symbol into Debug FIFO

-        //

-        DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Terminal Timer attach symbol received %x", *Data8);

-        DebugTerminalFifoAdd (&mSerialFifoForDebug, *Data8);

-      } else if (*Data8 == DEBUG_STARTING_SYMBOL_NORMAL) {

-        Status = ReadRemainingBreakPacket (Handle, &DebugHeader);

-        if (Status == EFI_SUCCESS) {

-          DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Terminal Timer break symbol received %x", DebugHeader.Command);

-          DebugTerminalFifoAdd (&mSerialFifoForDebug, DebugHeader.Command);

-        }

-

-        if (Status == EFI_TIMEOUT) {

-          continue;

-        }

-      } else {

-        *Uint8Buffer = *Data8;

-        Uint8Buffer++;

-      }

-    }

-

-    *BufferSize = (UINTN)Uint8Buffer - (UINTN)Buffer;

-  }

-

-  //

-  // Restore Debug Timer interrupt

-  //

-  SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);

-

-  //

-  // Restore to original TPL

-  //

-  gBS->RestoreTPL (Tpl);

-

-  return EFI_SUCCESS;

-}

-

-/**

-  Read the Attach/Break-in symbols from the debug port.

-

-  @param[in]  Handle         Pointer to Debug Port handle.

-  @param[out] BreakSymbol    Returned break symbol.

-

-  @retval EFI_SUCCESS        Read the symbol in BreakSymbol.

-  @retval EFI_NOT_FOUND      No read the break symbol.

-

-**/

-EFI_STATUS

-DebugReadBreakFromDebugPort (

-  IN  DEBUG_PORT_HANDLE  Handle,

-  OUT UINT8              *BreakSymbol

-  )

-{

-  EFI_STATUS           Status;

-  DEBUG_PACKET_HEADER  DebugHeader;

-  UINT8                *Data8;

-

-  *BreakSymbol = 0;

-  //

-  // If Debug Port buffer has data, read it till it was break symbol or Debug Port buffer empty.

-  //

-  Data8 = (UINT8 *)&DebugHeader;

-  while (TRUE) {

-    //

-    // If start symbol is not received

-    //

-    if (!DebugPortPollBuffer (Handle)) {

-      //

-      // If no data in Debug Port, exit

-      //

-      break;

-    }

-

-    //

-    // Try to read the start symbol

-    //

-    DebugAgentReadBuffer (Handle, Data8, 1, 0);

-    if (*Data8 == DEBUG_STARTING_SYMBOL_ATTACH) {

-      DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Debug Timer attach symbol received %x", *Data8);

-      *BreakSymbol = *Data8;

-      return EFI_SUCCESS;

-    }

-

-    if (*Data8 == DEBUG_STARTING_SYMBOL_NORMAL) {

-      Status = ReadRemainingBreakPacket (Handle, &DebugHeader);

-      if (Status == EFI_SUCCESS) {

-        DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Debug Timer break symbol received %x", DebugHeader.Command);

-        *BreakSymbol = DebugHeader.Command;

-        return EFI_SUCCESS;

-      }

-

-      if (Status == EFI_TIMEOUT) {

-        break;

-      }

-    } else {

-      //

-      // Add to Terminal FIFO

-      //

-      DebugTerminalFifoAdd (&mSerialFifoForTerminal, *Data8);

-    }

-  }

-

-  return EFI_NOT_FOUND;

-}

-

-/**

-  Read the Attach/Break-in symbols.

-

-  @param[in]  Handle         Pointer to Debug Port handle.

-  @param[out] BreakSymbol    Returned break symbol.

-

-  @retval EFI_SUCCESS        Read the symbol in BreakSymbol.

-  @retval EFI_NOT_FOUND      No read the break symbol.

-

-**/

-EFI_STATUS

-DebugReadBreakSymbol (

-  IN  DEBUG_PORT_HANDLE  Handle,

-  OUT UINT8              *BreakSymbol

-  )

-{

-  EFI_STATUS  Status;

-  UINT8       Data8;

-

-  //

-  // Read break symbol from debug FIFO firstly

-  //

-  Status = DebugTerminalFifoRemove (&mSerialFifoForDebug, &Data8);

-  if (Status == EFI_SUCCESS) {

-    *BreakSymbol = Data8;

-    return EFI_SUCCESS;

-  } else {

-    //

-    // Read Break symbol from debug port

-    //

-    return DebugReadBreakFromDebugPort (Handle, BreakSymbol);

-  }

-}

+/** @file
+  Install Serial IO Protocol that layers on top of a Debug Communication Library instance.
+
+  Copyright (c) 2012 - 2018, Intel Corporation. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "DxeDebugAgentLib.h"
+
+//
+// Serial I/O Protocol Interface definitions.
+//
+
+/**
+  Reset serial device.
+
+  @param[in] This           Pointer to EFI_SERIAL_IO_PROTOCOL.
+
+  @retval EFI_SUCCESS       Reset successfully.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialReset (
+  IN EFI_SERIAL_IO_PROTOCOL  *This
+  );
+
+/**
+  Set new attributes to a serial device.
+
+  @param[in]  This                Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[in]  BaudRate            The baudrate of the serial device.
+  @param[in]  ReceiveFifoDepth    The depth of receive FIFO buffer.
+  @param[in]  Timeout             The request timeout for a single char.
+  @param[in]  Parity              The type of parity used in serial device.
+  @param[in]  DataBits            Number of databits used in serial device.
+  @param[in]  StopBits            Number of stopbits used in serial device.
+
+  @retval EFI_SUCCESS             The new attributes were set.
+  @retval EFI_INVALID_PARAMETER   One or more attributes have an unsupported value.
+  @retval EFI_DEVICE_ERROR        The serial device is not functioning correctly (no return).
+
+**/
+EFI_STATUS
+EFIAPI
+SerialSetAttributes (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  IN UINT64                  BaudRate,
+  IN UINT32                  ReceiveFifoDepth,
+  IN UINT32                  Timeout,
+  IN EFI_PARITY_TYPE         Parity,
+  IN UINT8                   DataBits,
+  IN EFI_STOP_BITS_TYPE      StopBits
+  );
+
+/**
+  Set Control Bits.
+
+  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[in] Control         Control bits that can be settable.
+
+  @retval EFI_SUCCESS        New Control bits were set successfully.
+  @retval EFI_UNSUPPORTED    The Control bits wanted to set are not supported.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialSetControl (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  IN UINT32                  Control
+  );
+
+/**
+  Get ControlBits.
+
+  @param[in]  This         Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[out] Control      Control signals of the serial device.
+
+  @retval EFI_SUCCESS  Get Control signals successfully.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialGetControl (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  OUT UINT32                 *Control
+  );
+
+/**
+  Write the specified number of bytes to serial device.
+
+  @param[in]      This       Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[in, out] BufferSize On input the size of Buffer, on output the amount of
+                             data actually written.
+  @param[in]      Buffer     The buffer of data to write.
+
+  @retval EFI_SUCCESS        The data were written successfully.
+  @retval EFI_DEVICE_ERROR   The device reported an error.
+  @retval EFI_TIMEOUT        The write operation was stopped due to timeout.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialWrite (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  IN OUT UINTN               *BufferSize,
+  IN VOID                    *Buffer
+  );
+
+/**
+  Read the specified number of bytes from serial device.
+
+  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[in, out] BufferSize On input the size of Buffer, on output the amount of
+                             data returned in buffer.
+  @param[out] Buffer         The buffer to return the data into.
+
+  @retval EFI_SUCCESS        The data were read successfully.
+  @retval EFI_DEVICE_ERROR   The device reported an error.
+  @retval EFI_TIMEOUT        The read operation was stopped due to timeout.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialRead (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  IN OUT UINTN               *BufferSize,
+  OUT VOID                   *Buffer
+  );
+
+//
+// Serial Driver Defaults
+//
+#define SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH  1
+#define SERIAL_PORT_DEFAULT_TIMEOUT             1000000
+#define SERIAL_PORT_DEFAULT_CONTROL_MASK        0
+#define SERIAL_PORT_LOOPBACK_BUFFER_FULL        BIT8
+
+//
+// EFI_SERIAL_IO_MODE instance
+//
+EFI_SERIAL_IO_MODE  mSerialIoMode = {
+  SERIAL_PORT_DEFAULT_CONTROL_MASK,
+  SERIAL_PORT_DEFAULT_TIMEOUT,
+  0,  // default BaudRate
+  SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH,
+  0,  // default DataBits
+  0,  // default Parity
+  0   // default StopBits
+};
+
+//
+// EFI_SERIAL_IO_PROTOCOL instance
+//
+EFI_SERIAL_IO_PROTOCOL  mSerialIo = {
+  SERIAL_IO_INTERFACE_REVISION,
+  SerialReset,
+  SerialSetAttributes,
+  SerialSetControl,
+  SerialGetControl,
+  SerialWrite,
+  SerialRead,
+  &mSerialIoMode
+};
+
+//
+// Serial IO Device Path definition
+//
+typedef struct {
+  VENDOR_DEVICE_PATH          VendorDevicePath;
+  UART_DEVICE_PATH            UartDevicePath;
+  EFI_DEVICE_PATH_PROTOCOL    EndDevicePath;
+} SERIAL_IO_DEVICE_PATH;
+
+//
+// Serial IO Device Patch instance
+//
+SERIAL_IO_DEVICE_PATH  mSerialIoDevicePath = {
+  {
+    {
+      HARDWARE_DEVICE_PATH,
+      HW_VENDOR_DP,
+      {
+        (UINT8)(sizeof (VENDOR_DEVICE_PATH)),
+        (UINT8)((sizeof (VENDOR_DEVICE_PATH)) >> 8)
+      }
+    },
+    EFI_DEBUG_AGENT_GUID,
+  },
+  {
+    {
+      MESSAGING_DEVICE_PATH,
+      MSG_UART_DP,
+      {
+        (UINT8)(sizeof (UART_DEVICE_PATH)),
+        (UINT8)((sizeof (UART_DEVICE_PATH)) >> 8)
+      }
+    },
+    0,
+    0,  // default BaudRate
+    0,  // default DataBits
+    0,  // default Parity
+    0,  // default StopBits
+  },
+  {
+    END_DEVICE_PATH_TYPE,
+    END_ENTIRE_DEVICE_PATH_SUBTYPE,
+    {
+      END_DEVICE_PATH_LENGTH,
+      0
+    }
+  }
+};
+
+#define DEBUG_SERIAL_IO_FIFO_DEPTH  10
+//
+//  Data buffer for Terminal input character and Debug Symbols.
+//  The depth is DEBUG_SERIAL_IO_FIFO_DEPTH.
+//  Fields:
+//      First   UINT8: The index of the first data in array Data[].
+//      Last    UINT8: The index, which you can put a new data into array Data[].
+//      Surplus UINT8: Identify how many data you can put into array Data[].
+//      Data[]  UINT8: An array, which used to store data.
+//
+typedef struct {
+  UINT8    First;
+  UINT8    Last;
+  UINT8    Surplus;
+  UINT8    Data[DEBUG_SERIAL_IO_FIFO_DEPTH];
+} DEBUG_SERIAL_FIFO;
+
+//
+// Global Variables
+//
+EFI_HANDLE         mSerialIoHandle        = NULL;
+UINTN              mLoopbackBuffer        = 0;
+DEBUG_SERIAL_FIFO  mSerialFifoForTerminal = {
+  0, 0, DEBUG_SERIAL_IO_FIFO_DEPTH, { 0 }
+};
+DEBUG_SERIAL_FIFO  mSerialFifoForDebug = {
+  0, 0, DEBUG_SERIAL_IO_FIFO_DEPTH, { 0 }
+};
+
+/**
+  Detect whether specific FIFO is empty or not.
+
+  @param[in]  Fifo    A pointer to the Data Structure DEBUG_SERIAL_FIFO.
+
+  @return whether specific FIFO is empty or not.
+
+**/
+BOOLEAN
+IsDebugTerminalFifoEmpty (
+  IN DEBUG_SERIAL_FIFO  *Fifo
+  )
+{
+  if (Fifo->Surplus == DEBUG_SERIAL_IO_FIFO_DEPTH) {
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
+/**
+  Detect whether specific FIFO is full or not.
+
+  @param[in] Fifo    A pointer to the Data Structure DEBUG_SERIAL_FIFO.
+
+  @return whether specific FIFO is full or not.
+
+**/
+BOOLEAN
+IsDebugTerminalFifoFull (
+  IN DEBUG_SERIAL_FIFO  *Fifo
+  )
+
+{
+  if (Fifo->Surplus == 0) {
+    return TRUE;
+  }
+
+  return FALSE;
+}
+
+/**
+  Add data to specific FIFO.
+
+  @param[in] Fifo               A pointer to the Data Structure DEBUG_SERIAL_FIFO.
+  @param[in] Data               The data added to FIFO.
+
+  @retval EFI_SUCCESS           Add data to specific FIFO successfully.
+  @retval EFI_OUT_OF_RESOURCE   Failed to add data because FIFO is already full.
+
+**/
+EFI_STATUS
+DebugTerminalFifoAdd (
+  IN DEBUG_SERIAL_FIFO  *Fifo,
+  IN UINT8              Data
+  )
+
+{
+  //
+  // if FIFO full can not add data
+  //
+  if (IsDebugTerminalFifoFull (Fifo)) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  //
+  // FIFO is not full can add data
+  //
+  Fifo->Data[Fifo->Last] = Data;
+  Fifo->Surplus--;
+  Fifo->Last++;
+  if (Fifo->Last == DEBUG_SERIAL_IO_FIFO_DEPTH) {
+    Fifo->Last = 0;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Remove data from specific FIFO.
+
+  @param[in]  Fifo              A pointer to the Data Structure DEBUG_SERIAL_FIFO.
+  @param[out] Data              The data removed from FIFO.
+
+  @retval EFI_SUCCESS           Remove data from specific FIFO successfully.
+  @retval EFI_OUT_OF_RESOURCE   Failed to remove data because FIFO is empty.
+
+**/
+EFI_STATUS
+DebugTerminalFifoRemove (
+  IN  DEBUG_SERIAL_FIFO  *Fifo,
+  OUT UINT8              *Data
+  )
+{
+  //
+  // if FIFO is empty, no data can remove
+  //
+  if (IsDebugTerminalFifoEmpty (Fifo)) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  //
+  // FIFO is not empty, can remove data
+  //
+  *Data = Fifo->Data[Fifo->First];
+  Fifo->Surplus++;
+  Fifo->First++;
+  if (Fifo->First == DEBUG_SERIAL_IO_FIFO_DEPTH) {
+    Fifo->First = 0;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Install EFI Serial IO protocol based on Debug Communication Library.
+
+**/
+VOID
+InstallSerialIo (
+  VOID
+  )
+{
+  EFI_STATUS  Status;
+
+  Status = gBS->InstallMultipleProtocolInterfaces (
+                  &mSerialIoHandle,
+                  &gEfiDevicePathProtocolGuid,
+                  &mSerialIoDevicePath,
+                  &gEfiSerialIoProtocolGuid,
+                  &mSerialIo,
+                  NULL
+                  );
+  if (EFI_ERROR (Status)) {
+    DEBUG ((DEBUG_ERROR, "Debug Agent: Failed to install EFI Serial IO Protocol on Debug Port!\n"));
+  }
+}
+
+/**
+  Reset serial device.
+
+  @param[in] This           Pointer to EFI_SERIAL_IO_PROTOCOL.
+
+  @retval EFI_SUCCESS       Reset successfully.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialReset (
+  IN EFI_SERIAL_IO_PROTOCOL  *This
+  )
+{
+  mSerialIoMode.ControlMask = SERIAL_PORT_DEFAULT_CONTROL_MASK;
+  mLoopbackBuffer           = 0;
+  //
+  // Not reset serial device hardware indeed.
+  //
+  return EFI_SUCCESS;
+}
+
+/**
+  Set new attributes to a serial device.
+
+  @param[in]  This                Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[in]  BaudRate            The baudrate of the serial device.
+  @param[in]  ReceiveFifoDepth    The depth of receive FIFO buffer.
+  @param[in]  Timeout             The request timeout for a single char.
+  @param[in]  Parity              The type of parity used in serial device.
+  @param[in]  DataBits            Number of databits used in serial device.
+  @param[in]  StopBits            Number of stopbits used in serial device.
+
+  @retval EFI_SUCCESS             The new attributes were set.
+  @retval EFI_INVALID_PARAMETER   One or more attributes have an unsupported value.
+  @retval EFI_DEVICE_ERROR        The serial device is not functioning correctly (no return).
+
+**/
+EFI_STATUS
+EFIAPI
+SerialSetAttributes (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  IN UINT64                  BaudRate,
+  IN UINT32                  ReceiveFifoDepth,
+  IN UINT32                  Timeout,
+  IN EFI_PARITY_TYPE         Parity,
+  IN UINT8                   DataBits,
+  IN EFI_STOP_BITS_TYPE      StopBits
+  )
+{
+  //
+  // The Debug Communication Library CAN NOT change communications parameters (if it has)
+  // actually. Because it also has no any idea on what parameters are based on, we cannot
+  // check the input parameters (like BaudRate, Parity, DataBits and StopBits).
+  //
+
+  //
+  // Update the Timeout value in the mode structure based on the request.
+  // The Debug Communication Library can not support a timeout on writes, but the timeout on
+  // reads can be provided by this module.
+  //
+  if (Timeout == 0) {
+    mSerialIoMode.Timeout = SERIAL_PORT_DEFAULT_TIMEOUT;
+  } else {
+    mSerialIoMode.Timeout = Timeout;
+  }
+
+  //
+  // Update the ReceiveFifoDepth value in the mode structure based on the request.
+  // This module assumes that the Debug Communication Library uses a FIFO depth of
+  // SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH.  The Debug Communication Library may actually be
+  // using a larger FIFO, but there is no way to tell.
+  //
+  if ((ReceiveFifoDepth == 0) || (ReceiveFifoDepth >= SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH)) {
+    mSerialIoMode.ReceiveFifoDepth = SERIAL_PORT_DEFAULT_RECEIVE_FIFO_DEPTH;
+  } else {
+    return EFI_INVALID_PARAMETER;
+  }
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Set Control Bits.
+
+  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[in] Control         Control bits that can be settable.
+
+  @retval EFI_SUCCESS        New Control bits were set successfully.
+  @retval EFI_UNSUPPORTED    The Control bits wanted to set are not supported.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialSetControl (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  IN UINT32                  Control
+  )
+{
+  //
+  // The only control bit supported by this module is software loopback.
+  // If any other bit is set, then return an error
+  //
+  if ((Control & (~EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE)) != 0) {
+    return EFI_UNSUPPORTED;
+  }
+
+  mSerialIoMode.ControlMask = Control;
+  return EFI_SUCCESS;
+}
+
+/**
+  Get ControlBits.
+
+  @param[in]  This         Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[out] Control      Control signals of the serial device.
+
+  @retval EFI_SUCCESS  Get Control signals successfully.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialGetControl (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  OUT UINT32                 *Control
+  )
+{
+  DEBUG_PORT_HANDLE  Handle;
+  BOOLEAN            DebugTimerInterruptState;
+  EFI_TPL            Tpl;
+
+  //
+  // Raise TPL to prevent recursion from EFI timer interrupts
+  //
+  Tpl = gBS->RaiseTPL (TPL_NOTIFY);
+
+  //
+  // Save and disable Debug Timer interrupt to avoid it to access Debug Port
+  //
+  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);
+  Handle                   = GetDebugPortHandle ();
+
+  //
+  // Always assume the output buffer is empty and the Debug Communication Library can process
+  // more write requests.
+  //
+  *Control = mSerialIoMode.ControlMask | EFI_SERIAL_OUTPUT_BUFFER_EMPTY;
+
+  //
+  // Check to see if the Terminal FIFO is empty and
+  // check to see if the input buffer in the Debug Communication Library is empty
+  //
+  if (!IsDebugTerminalFifoEmpty (&mSerialFifoForTerminal) || DebugPortPollBuffer (Handle)) {
+    *Control &= ~EFI_SERIAL_INPUT_BUFFER_EMPTY;
+  }
+
+  //
+  // Restore Debug Timer interrupt
+  //
+  SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);
+
+  //
+  // Restore to original TPL
+  //
+  gBS->RestoreTPL (Tpl);
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Write the specified number of bytes to serial device.
+
+  @param[in]      This       Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[in, out] BufferSize On input the size of Buffer, on output the amount of
+                             data actually written.
+  @param[in]      Buffer     The buffer of data to write.
+
+  @retval EFI_SUCCESS        The data were written successfully.
+  @retval EFI_DEVICE_ERROR   The device reported an error.
+  @retval EFI_TIMEOUT        The write operation was stopped due to timeout.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialWrite (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  IN OUT UINTN               *BufferSize,
+  IN VOID                    *Buffer
+  )
+{
+  DEBUG_PORT_HANDLE  Handle;
+  BOOLEAN            DebugTimerInterruptState;
+  EFI_TPL            Tpl;
+
+  //
+  // Raise TPL to prevent recursion from EFI timer interrupts
+  //
+  Tpl = gBS->RaiseTPL (TPL_NOTIFY);
+
+  //
+  // Save and disable Debug Timer interrupt to avoid it to access Debug Port
+  //
+  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);
+  Handle                   = GetDebugPortHandle ();
+
+  if ((mSerialIoMode.ControlMask & EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE) != 0) {
+    if (*BufferSize == 0) {
+      return EFI_SUCCESS;
+    }
+
+    if ((mLoopbackBuffer & SERIAL_PORT_LOOPBACK_BUFFER_FULL) != 0) {
+      *BufferSize = 0;
+      return EFI_TIMEOUT;
+    }
+
+    mLoopbackBuffer = SERIAL_PORT_LOOPBACK_BUFFER_FULL | *(UINT8 *)Buffer;
+    *BufferSize     = 1;
+  } else {
+    *BufferSize = DebugPortWriteBuffer (Handle, Buffer, *BufferSize);
+  }
+
+  //
+  // Restore Debug Timer interrupt
+  //
+  SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);
+
+  //
+  // Restore to original TPL
+  //
+  gBS->RestoreTPL (Tpl);
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Read the specified number of bytes from serial device.
+
+  @param[in] This            Pointer to EFI_SERIAL_IO_PROTOCOL.
+  @param[in, out] BufferSize On input the size of Buffer, on output the amount of
+                             data returned in buffer.
+  @param[out] Buffer         The buffer to return the data into.
+
+  @retval EFI_SUCCESS        The data were read successfully.
+  @retval EFI_DEVICE_ERROR   The device reported an error.
+  @retval EFI_TIMEOUT        The read operation was stopped due to timeout.
+
+**/
+EFI_STATUS
+EFIAPI
+SerialRead (
+  IN EFI_SERIAL_IO_PROTOCOL  *This,
+  IN OUT UINTN               *BufferSize,
+  OUT VOID                   *Buffer
+  )
+{
+  EFI_STATUS           Status;
+  UINTN                Index;
+  UINT8                *Uint8Buffer;
+  BOOLEAN              DebugTimerInterruptState;
+  EFI_TPL              Tpl;
+  DEBUG_PORT_HANDLE    Handle;
+  DEBUG_PACKET_HEADER  DebugHeader;
+  UINT8                *Data8;
+
+  //
+  // Raise TPL to prevent recursion from EFI timer interrupts
+  //
+  Tpl = gBS->RaiseTPL (TPL_NOTIFY);
+
+  //
+  // Save and disable Debug Timer interrupt to avoid it to access Debug Port
+  //
+  DebugTimerInterruptState = SaveAndSetDebugTimerInterrupt (FALSE);
+  Handle                   = GetDebugPortHandle ();
+
+  Data8       = (UINT8 *)&DebugHeader;
+  Uint8Buffer = (UINT8 *)Buffer;
+  if ((mSerialIoMode.ControlMask & EFI_SERIAL_SOFTWARE_LOOPBACK_ENABLE) != 0) {
+    if ((mLoopbackBuffer & SERIAL_PORT_LOOPBACK_BUFFER_FULL) == 0) {
+      return EFI_TIMEOUT;
+    }
+
+    *Uint8Buffer    = (UINT8)(mLoopbackBuffer & 0xff);
+    mLoopbackBuffer = 0;
+    *BufferSize     = 1;
+  } else {
+    for (Index = 0; Index < *BufferSize; Index++) {
+      //
+      // Read input character from terminal FIFO firstly
+      //
+      Status = DebugTerminalFifoRemove (&mSerialFifoForTerminal, Data8);
+      if (Status == EFI_SUCCESS) {
+        *Uint8Buffer = *Data8;
+        Uint8Buffer++;
+        continue;
+      }
+
+      //
+      // Read the input character from Debug Port
+      //
+      if (!DebugPortPollBuffer (Handle)) {
+        break;
+      }
+
+      DebugAgentReadBuffer (Handle, Data8, 1, 0);
+
+      if (*Data8 == DEBUG_STARTING_SYMBOL_ATTACH) {
+        //
+        // Add the debug symbol into Debug FIFO
+        //
+        DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Terminal Timer attach symbol received %x", *Data8);
+        DebugTerminalFifoAdd (&mSerialFifoForDebug, *Data8);
+      } else if (*Data8 == DEBUG_STARTING_SYMBOL_NORMAL) {
+        Status = ReadRemainingBreakPacket (Handle, &DebugHeader);
+        if (Status == EFI_SUCCESS) {
+          DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Terminal Timer break symbol received %x", DebugHeader.Command);
+          DebugTerminalFifoAdd (&mSerialFifoForDebug, DebugHeader.Command);
+        }
+
+        if (Status == EFI_TIMEOUT) {
+          continue;
+        }
+      } else {
+        *Uint8Buffer = *Data8;
+        Uint8Buffer++;
+      }
+    }
+
+    *BufferSize = (UINTN)Uint8Buffer - (UINTN)Buffer;
+  }
+
+  //
+  // Restore Debug Timer interrupt
+  //
+  SaveAndSetDebugTimerInterrupt (DebugTimerInterruptState);
+
+  //
+  // Restore to original TPL
+  //
+  gBS->RestoreTPL (Tpl);
+
+  return EFI_SUCCESS;
+}
+
+/**
+  Read the Attach/Break-in symbols from the debug port.
+
+  @param[in]  Handle         Pointer to Debug Port handle.
+  @param[out] BreakSymbol    Returned break symbol.
+
+  @retval EFI_SUCCESS        Read the symbol in BreakSymbol.
+  @retval EFI_NOT_FOUND      No read the break symbol.
+
+**/
+EFI_STATUS
+DebugReadBreakFromDebugPort (
+  IN  DEBUG_PORT_HANDLE  Handle,
+  OUT UINT8              *BreakSymbol
+  )
+{
+  EFI_STATUS           Status;
+  DEBUG_PACKET_HEADER  DebugHeader;
+  UINT8                *Data8;
+
+  *BreakSymbol = 0;
+  //
+  // If Debug Port buffer has data, read it till it was break symbol or Debug Port buffer empty.
+  //
+  Data8 = (UINT8 *)&DebugHeader;
+  while (TRUE) {
+    //
+    // If start symbol is not received
+    //
+    if (!DebugPortPollBuffer (Handle)) {
+      //
+      // If no data in Debug Port, exit
+      //
+      break;
+    }
+
+    //
+    // Try to read the start symbol
+    //
+    DebugAgentReadBuffer (Handle, Data8, 1, 0);
+    if (*Data8 == DEBUG_STARTING_SYMBOL_ATTACH) {
+      DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Debug Timer attach symbol received %x", *Data8);
+      *BreakSymbol = *Data8;
+      return EFI_SUCCESS;
+    }
+
+    if (*Data8 == DEBUG_STARTING_SYMBOL_NORMAL) {
+      Status = ReadRemainingBreakPacket (Handle, &DebugHeader);
+      if (Status == EFI_SUCCESS) {
+        DebugAgentMsgPrint (DEBUG_AGENT_INFO, "Debug Timer break symbol received %x", DebugHeader.Command);
+        *BreakSymbol = DebugHeader.Command;
+        return EFI_SUCCESS;
+      }
+
+      if (Status == EFI_TIMEOUT) {
+        break;
+      }
+    } else {
+      //
+      // Add to Terminal FIFO
+      //
+      DebugTerminalFifoAdd (&mSerialFifoForTerminal, *Data8);
+    }
+  }
+
+  return EFI_NOT_FOUND;
+}
+
+/**
+  Read the Attach/Break-in symbols.
+
+  @param[in]  Handle         Pointer to Debug Port handle.
+  @param[out] BreakSymbol    Returned break symbol.
+
+  @retval EFI_SUCCESS        Read the symbol in BreakSymbol.
+  @retval EFI_NOT_FOUND      No read the break symbol.
+
+**/
+EFI_STATUS
+DebugReadBreakSymbol (
+  IN  DEBUG_PORT_HANDLE  Handle,
+  OUT UINT8              *BreakSymbol
+  )
+{
+  EFI_STATUS  Status;
+  UINT8       Data8;
+
+  //
+  // Read break symbol from debug FIFO firstly
+  //
+  Status = DebugTerminalFifoRemove (&mSerialFifoForDebug, &Data8);
+  if (Status == EFI_SUCCESS) {
+    *BreakSymbol = Data8;
+    return EFI_SUCCESS;
+  } else {
+    //
+    // Read Break symbol from debug port
+    //
+    return DebugReadBreakFromDebugPort (Handle, BreakSymbol);
+  }
+}