kiinit.c

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/*
 * PROJECT:         ReactOS Kernel
 * LICENSE:         GPL - See COPYING in the top level directory
 * FILE:            ntoskrnl/ke/amd64/kiinit.c
 * PURPOSE:         Kernel Initialization for x86 CPUs
 * PROGRAMMERS:     Alex Ionescu (alex.ionescu@reactos.org)
 *                  Timo Kreuzer (timo.kreuzer@reactos.org)
 */
 
/* INCLUDES *****************************************************************/
 
#include <ntoskrnl.h>
#define NDEBUG
#include <debug.h>
 
#define REQUIRED_FEATURE_BITS (KF_RDTSC|KF_CR4|KF_CMPXCHG8B|KF_XMMI|KF_XMMI64| \
                               KF_LARGE_PAGE|KF_FAST_SYSCALL|KF_GLOBAL_PAGE| \
                               KF_CMOV|KF_PAT|KF_MMX|KF_FXSR|KF_NX_BIT|KF_MTRR)
 
/* GLOBALS *******************************************************************/
 
/* Function pointer for early debug prints */
ULONG (*FrLdrDbgPrint)(const char *Format, ...);
 
/* Spinlocks used only on X86 */
KSPIN_LOCK KiFreezeExecutionLock;
 
 
KIPCR KiInitialPcr;
 
/* Boot and double-fault/NMI/DPC stack */
UCHAR DECLSPEC_ALIGN(16) KiP0BootStackData[KERNEL_STACK_SIZE] = {0};
UCHAR DECLSPEC_ALIGN(16) KiP0DoubleFaultStackData[KERNEL_STACK_SIZE] = {0};
PVOID KiP0BootStack = &KiP0BootStackData[KERNEL_STACK_SIZE];
PVOID KiP0DoubleFaultStack = &KiP0DoubleFaultStackData[KERNEL_STACK_SIZE];
 
ULONGLONG BootCycles, BootCyclesEnd;
 
void KiInitializeSegments();
void KiSystemCallEntry64();
void KiSystemCallEntry32();
 
/* FUNCTIONS *****************************************************************/
 
CODE_SEG("INIT")
VOID
NTAPI
KiInitMachineDependent(VOID)
{
    /* Check for large page support */
    if (KeFeatureBits & KF_LARGE_PAGE)
    {
        /* FIXME: Support this */
        DPRINT("Large Page support detected but not yet taken advantage of!\n");
    }
 
    /* Check for global page support */
    if (KeFeatureBits & KF_GLOBAL_PAGE)
    {
        /* FIXME: Support this */
        DPRINT("Global Page support detected but not yet taken advantage of!\n");
    }
 
    /* Check if we have MTRR */
    if (KeFeatureBits & KF_MTRR)
    {
        /* FIXME: Support this */
        DPRINT("MTRR support detected but not yet taken advantage of!\n");
    }
 
    /* Check for PAT and/or MTRR support */
    if (KeFeatureBits & KF_PAT)
    {
        /* FIXME: Support this */
        DPRINT("PAT support detected but not yet taken advantage of!\n");
    }
 
//        /* Allocate the IOPM save area */
//        Ki386IopmSaveArea = ExAllocatePoolWithTag(PagedPool,
//                                                  IOPM_SIZE,
//                                                  '  eK');
//        if (!Ki386IopmSaveArea)
//        {
//            /* Bugcheck. We need this for V86/VDM support. */
//            KeBugCheckEx(NO_PAGES_AVAILABLE, 2, IOPM_SIZE, 0, 0);
//        }
 
}
 
static
VOID
KiInitializePcr(
    _Out_ PKIPCR Pcr,
    _In_ ULONG ProcessorNumber,
    _In_ PKGDTENTRY64 GdtBase,
    _In_ PKIDTENTRY64 IdtBase,
    _In_ PKTSS64 TssBase,
    _In_ PKTHREAD IdleThread,
    _In_ PVOID DpcStack)
{
    /* Zero out the PCR */
    RtlZeroMemory(Pcr, sizeof(KIPCR));
 
    /* Set pointers to ourselves */
    Pcr->Self = (PKPCR)Pcr;
    Pcr->CurrentPrcb = &Pcr->Prcb;
 
    /* Set the PCR Version */
    Pcr->MajorVersion = PCR_MAJOR_VERSION;
    Pcr->MinorVersion = PCR_MINOR_VERSION;
 
    /* Set the PRCB Version */
    Pcr->Prcb.MajorVersion = PRCB_MAJOR_VERSION;
    Pcr->Prcb.MinorVersion = PRCB_MINOR_VERSION;
 
    /* Set the Build Type */
    Pcr->Prcb.BuildType = 0;
#ifndef CONFIG_SMP
    Pcr->Prcb.BuildType |= PRCB_BUILD_UNIPROCESSOR;
#endif
#if DBG
    Pcr->Prcb.BuildType |= PRCB_BUILD_DEBUG;
#endif
 
    /* Set the Processor Number and current Processor Mask */
    Pcr->Prcb.Number = (UCHAR)ProcessorNumber;
    Pcr->Prcb.SetMember = 1ULL << ProcessorNumber;
 
    /* Set GDT and IDT base */
    Pcr->GdtBase = GdtBase;
    Pcr->IdtBase = IdtBase;
 
    /* Set TssBase */
    Pcr->TssBase = TssBase;
 
    Pcr->Prcb.RspBase = Pcr->TssBase->Rsp0; // FIXME
 
    /* Set DPC Stack */
    Pcr->Prcb.DpcStack = DpcStack;
 
    /* Setup the processor set */
    Pcr->Prcb.MultiThreadProcessorSet = Pcr->Prcb.SetMember;
 
    /* Clear DR6/7 to cleanup bootloader debugging */
    Pcr->Prcb.ProcessorState.SpecialRegisters.KernelDr6 = 0;
    Pcr->Prcb.ProcessorState.SpecialRegisters.KernelDr7 = 0;
 
    /* Initialize MXCSR (all exceptions masked) */
    Pcr->Prcb.MxCsr = INITIAL_MXCSR;
 
    /* Set the Current Thread */
    Pcr->Prcb.CurrentThread = IdleThread;
 
    /* Start us out at PASSIVE_LEVEL */
    Pcr->Irql = PASSIVE_LEVEL;
}
 
VOID
NTAPI
KiInitializeCpu(PKIPCR Pcr)
{
    ULONG64 Pat;
    ULONG64 FeatureBits;
 
    /* Initialize gs */
    KiInitializeSegments();
 
    /* Set GS base */
    __writemsr(MSR_GS_BASE, (ULONG64)Pcr);
    __writemsr(MSR_GS_SWAP, (ULONG64)Pcr);
 
    /* Detect and set the CPU Type */
    KiSetProcessorType();
 
    /* Get the processor features for this CPU */
    FeatureBits = KiGetFeatureBits();
 
    /* Check if we support all needed features */
    if ((FeatureBits & REQUIRED_FEATURE_BITS) != REQUIRED_FEATURE_BITS)
    {
        /* If not, bugcheck system */
        FrLdrDbgPrint("CPU doesn't have needed features! Has: 0x%x, required: 0x%x\n",
                FeatureBits, REQUIRED_FEATURE_BITS);
        KeBugCheck(0);
    }
 
    /* Set DEP to always on */
    SharedUserData->NXSupportPolicy = NX_SUPPORT_POLICY_ALWAYSON;
    FeatureBits |= KF_NX_ENABLED;
 
    /* Save feature bits */
    Pcr->Prcb.FeatureBits = (ULONG)FeatureBits;
    Pcr->Prcb.FeatureBitsHigh = FeatureBits >> 32;
 
    /* Enable fx save restore support */
    __writecr4(__readcr4() | CR4_FXSR);
 
    /* Enable XMMI exceptions */
    __writecr4(__readcr4() | CR4_XMMEXCPT);
 
    /* Enable Write-Protection */
    __writecr0(__readcr0() | CR0_WP);
 
    /* Disable fpu monitoring */
    __writecr0(__readcr0() & ~CR0_MP);
 
    /* Disable x87 fpu exceptions */
    __writecr0(__readcr0() & ~CR0_NE);
 
    /* Check if XSAVE is supported */
    if (FeatureBits & KF_XSTATE)
    {
        /* Enable CR4.OSXSAVE[Bit 18] */
        __writecr4(__readcr4() | CR4_XSAVE);
    }
 
    /* LDT is unused */
    __lldt(0);
 
    /* Set the systemcall entry points */
    __writemsr(MSR_LSTAR, (ULONG64)KiSystemCallEntry64);
    __writemsr(MSR_CSTAR, (ULONG64)KiSystemCallEntry32);
 
    __writemsr(MSR_STAR, ((ULONG64)KGDT64_R0_CODE << 32) |
                         ((ULONG64)(KGDT64_R3_CMCODE|RPL_MASK) << 48));
 
    /* Set the flags to be cleared when doing a syscall */
    __writemsr(MSR_SYSCALL_MASK, EFLAGS_IF_MASK | EFLAGS_TF | EFLAGS_DF | EFLAGS_NESTED_TASK);
 
    /* Enable syscall instruction and no-execute support */
    __writemsr(MSR_EFER, __readmsr(MSR_EFER) | MSR_SCE | MSR_NXE);
 
    /* Initialize the PAT */
    Pat = (PAT_WB << 0)  | (PAT_WC << 8) | (PAT_UCM << 16) | (PAT_UC << 24) |
          (PAT_WB << 32) | (PAT_WC << 40) | (PAT_UCM << 48) | (PAT_UC << 56);
    __writemsr(MSR_PAT, Pat);
 
    /* Initialize MXCSR */
    _mm_setcsr(INITIAL_MXCSR);
 
    KeSetCurrentIrql(PASSIVE_LEVEL);
}
 
static
VOID
KiInitializeTss(
    _In_ PKIPCR Pcr,
    _Out_ PKTSS64 Tss,
    _In_ PVOID InitialStack,
    _In_ PVOID DoubleFaultStack,
    _In_ PVOID NmiStack)
{
    PKGDTENTRY64 TssEntry;
 
    /* Get pointer to the GDT entry */
    TssEntry = KiGetGdtEntry(Pcr->GdtBase, KGDT64_SYS_TSS);
 
    /* Initialize the GDT entry */
    KiInitGdtEntry(TssEntry, (ULONG64)Tss, sizeof(KTSS64), AMD64_TSS, 0);
 
    /* Zero out the TSS */
    RtlZeroMemory(Tss, sizeof(KTSS64));
 
    /* FIXME: I/O Map? */
    Tss->IoMapBase = 0x68;
 
    /* Setup ring 0 stack pointer */
    Tss->Rsp0 = (ULONG64)InitialStack;
 
    /* Setup a stack for Double Fault Traps */
    Tss->Ist[1] = (ULONG64)DoubleFaultStack;
 
    /* Setup a stack for CheckAbort Traps */
    Tss->Ist[2] = (ULONG64)DoubleFaultStack;
 
    /* Setup a stack for NMI Traps */
    Tss->Ist[3] = (ULONG64)NmiStack;
}
 
CODE_SEG("INIT")
VOID
KiInitializeProcessorBootStructures(
    _In_ ULONG ProcessorNumber,
    _Out_ PKIPCR Pcr,
    _In_ PKGDTENTRY64 GdtBase,
    _In_ PKIDTENTRY64 IdtBase,
    _In_ PKTSS64 TssBase,
    _In_ PKTHREAD IdleThread,
    _In_ PVOID KernelStack,
    _In_ PVOID DpcStack,
    _In_ PVOID DoubleFaultStack,
    _In_ PVOID NmiStack)
{
    /* Initialize the PCR */
    KiInitializePcr(Pcr,
                    ProcessorNumber,
                    GdtBase,
                    IdtBase,
                    TssBase,
                    IdleThread,
                    DpcStack);
 
 
    /* Setup the TSS descriptor and entries */
    KiInitializeTss(Pcr,
                    TssBase,
                    KernelStack,
                    DoubleFaultStack,
                    NmiStack);
}
 
CODE_SEG("INIT")
static
VOID
KiInitializeP0BootStructures(
    _Inout_ PLOADER_PARAMETER_BLOCK LoaderBlock)
{
    KDESCRIPTOR GdtDescriptor = {{0},0,0}, IdtDescriptor = {{0},0,0};
    PKGDTENTRY64 TssEntry;
    PKTSS64 TssBase;
 
    /* Set the initial stack, idle thread and process for processor 0 */
    LoaderBlock->KernelStack = (ULONG_PTR)KiP0BootStack;
    LoaderBlock->Thread = (ULONG_PTR)&KiInitialThread;
    LoaderBlock->Process = (ULONG_PTR)&KiInitialProcess.Pcb;
    LoaderBlock->Prcb = (ULONG_PTR)&KiInitialPcr.Prcb;
 
    /* Get GDT and IDT descriptors */
    __sgdt(&GdtDescriptor.Limit);
    __sidt(&IdtDescriptor.Limit);
 
    /* Get the boot TSS from the GDT */
    TssEntry = KiGetGdtEntry(GdtDescriptor.Base, KGDT64_SYS_TSS);
    TssBase = KiGetGdtDescriptorBase(TssEntry);
 
    /* Initialize PCR and TSS */
    KiInitializeProcessorBootStructures(0,
                                        &KiInitialPcr,
                                        GdtDescriptor.Base,
                                        IdtDescriptor.Base,
                                        TssBase,
                                        &KiInitialThread.Tcb,
                                        KiP0BootStack,
                                        KiP0DoubleFaultStack,
                                        KiP0DoubleFaultStack,
                                        KiP0DoubleFaultStack);
}
 
CODE_SEG("INIT")
VOID
NTAPI
KiInitializeKernelMachineDependent(
    IN PKPRCB Prcb,
    IN PLOADER_PARAMETER_BLOCK LoaderBlock)
{
    ULONG64 FeatureBits = KeFeatureBits;
 
    /* Set boot-level flags */
    KeI386CpuType = Prcb->CpuType;
    KeI386CpuStep = Prcb->CpuStep;
    KeProcessorArchitecture = PROCESSOR_ARCHITECTURE_AMD64;
    KeProcessorLevel = (USHORT)Prcb->CpuType;
    if (Prcb->CpuID)
        KeProcessorRevision = Prcb->CpuStep;
 
    /* Set basic CPU Features that user mode can read */
    SharedUserData->ProcessorFeatures[PF_FLOATING_POINT_PRECISION_ERRATA] = FALSE;
    SharedUserData->ProcessorFeatures[PF_FLOATING_POINT_EMULATED] = FALSE;
    SharedUserData->ProcessorFeatures[PF_COMPARE_EXCHANGE_DOUBLE] = TRUE;
    SharedUserData->ProcessorFeatures[PF_MMX_INSTRUCTIONS_AVAILABLE] =
        (FeatureBits & KF_MMX) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_XMMI_INSTRUCTIONS_AVAILABLE] =
        ((FeatureBits & KF_FXSR) && (FeatureBits & KF_XMMI)) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_3DNOW_INSTRUCTIONS_AVAILABLE] =
        (FeatureBits & KF_3DNOW) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_RDTSC_INSTRUCTION_AVAILABLE] = TRUE;
    SharedUserData->ProcessorFeatures[PF_PAE_ENABLED] = TRUE; // ???
    SharedUserData->ProcessorFeatures[PF_XMMI64_INSTRUCTIONS_AVAILABLE] =
        ((FeatureBits & KF_FXSR) && (FeatureBits & KF_XMMI64)) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_SSE_DAZ_MODE_AVAILABLE] = FALSE; // ???
    SharedUserData->ProcessorFeatures[PF_NX_ENABLED] = TRUE;
    SharedUserData->ProcessorFeatures[PF_SSE3_INSTRUCTIONS_AVAILABLE] =
        (FeatureBits & KF_SSE3) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_COMPARE_EXCHANGE128] =
        (FeatureBits & KF_CMPXCHG16B) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_COMPARE64_EXCHANGE128] = FALSE; // ???
    SharedUserData->ProcessorFeatures[PF_CHANNELS_ENABLED] = FALSE; // ???
    SharedUserData->ProcessorFeatures[PF_XSAVE_ENABLED] =
        (FeatureBits & KF_XSTATE) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_SECOND_LEVEL_ADDRESS_TRANSLATION] =
        (FeatureBits & KF_SLAT) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_VIRT_FIRMWARE_ENABLED] =
        (FeatureBits & KF_VIRT_FIRMWARE_ENABLED) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_RDWRFSGSBASE_AVAILABLE] =
        (FeatureBits & KF_RDWRFSGSBASE) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_FASTFAIL_AVAILABLE] = TRUE;
    SharedUserData->ProcessorFeatures[PF_RDRAND_INSTRUCTION_AVAILABLE] =
        (FeatureBits & KF_RDRAND) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_RDTSCP_INSTRUCTION_AVAILABLE] =
        (FeatureBits & KF_RDTSCP) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_RDPID_INSTRUCTION_AVAILABLE] = FALSE; // ???
    SharedUserData->ProcessorFeatures[PF_SSSE3_INSTRUCTIONS_AVAILABLE] =
        (FeatureBits & KF_SSSE3) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_SSE4_1_INSTRUCTIONS_AVAILABLE] =
        (FeatureBits & KF_SSE4_1) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_SSE4_2_INSTRUCTIONS_AVAILABLE] =
        (FeatureBits & KF_SSE4_2) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_AVX_INSTRUCTIONS_AVAILABLE] =
        (FeatureBits & KF_AVX) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_AVX2_INSTRUCTIONS_AVAILABLE] =
        (FeatureBits & KF_AVX2) ? TRUE : FALSE;
    SharedUserData->ProcessorFeatures[PF_AVX512F_INSTRUCTIONS_AVAILABLE] =
        (FeatureBits & KF_AVX512F) ? TRUE : FALSE;
 
    /* Set the default NX policy (opt-in) */
    SharedUserData->NXSupportPolicy = NX_SUPPORT_POLICY_OPTIN;
 
    /* Check if NPX is always on */
    if (strstr(KeLoaderBlock->LoadOptions, "NOEXECUTE=ALWAYSON"))
    {
        /* Set it always on */
        SharedUserData->NXSupportPolicy = NX_SUPPORT_POLICY_ALWAYSON;
        Prcb->FeatureBits |= KF_NX_ENABLED;
    }
    else if (strstr(KeLoaderBlock->LoadOptions, "NOEXECUTE=OPTOUT"))
    {
        /* Set it in opt-out mode */
        SharedUserData->NXSupportPolicy = NX_SUPPORT_POLICY_OPTOUT;
        Prcb->FeatureBits |= KF_NX_ENABLED;
    }
    else if ((strstr(KeLoaderBlock->LoadOptions, "NOEXECUTE=OPTIN")) ||
             (strstr(KeLoaderBlock->LoadOptions, "NOEXECUTE")))
    {
        /* Set the feature bits */
        Prcb->FeatureBits |= KF_NX_ENABLED;
    }
    else if ((strstr(KeLoaderBlock->LoadOptions, "NOEXECUTE=ALWAYSOFF")) ||
             (strstr(KeLoaderBlock->LoadOptions, "EXECUTE")))
    {
        /* Set disabled mode */
        SharedUserData->NXSupportPolicy = NX_SUPPORT_POLICY_ALWAYSOFF;
        Prcb->FeatureBits |= KF_NX_DISABLED;
    }
 
#if DBG
    /* Print applied kernel features/policies and boot CPU features */
    KiReportCpuFeatures(Prcb);
#endif
}
 
static LDR_DATA_TABLE_ENTRY LdrCoreEntries[3];
 
void
KiInitModuleList(IN PLOADER_PARAMETER_BLOCK LoaderBlock)
{
    PLDR_DATA_TABLE_ENTRY LdrEntry;
    PLIST_ENTRY Entry;
    ULONG i;
 
    /* Initialize the list head */
    InitializeListHead(&PsLoadedModuleList);
 
    /* Loop the first 3 entries */
    for (Entry = LoaderBlock->LoadOrderListHead.Flink, i = 0;
         Entry != &LoaderBlock->LoadOrderListHead && i < 3;
         Entry = Entry->Flink, i++)
    {
        /* Get the data table entry */
        LdrEntry = CONTAINING_RECORD(Entry,
                                     LDR_DATA_TABLE_ENTRY,
                                     InLoadOrderLinks);
 
        /* Copy the entry */
        LdrCoreEntries[i] = *LdrEntry;
 
        /* Insert the copy into the list */
        InsertTailList(&PsLoadedModuleList, &LdrCoreEntries[i].InLoadOrderLinks);
    }
}
 
CODE_SEG("INIT")
DECLSPEC_NORETURN
VOID
NTAPI
KiSystemStartup(IN PLOADER_PARAMETER_BLOCK LoaderBlock)
{
    CCHAR Cpu;
    PKTHREAD InitialThread;
    ULONG64 InitialStack;
    PKIPCR Pcr;
 
    /* Boot cycles timestamp */
    BootCycles = __rdtsc();
 
    /* HACK */
    FrLdrDbgPrint = LoaderBlock->u.I386.CommonDataArea;
    //FrLdrDbgPrint("Hello from KiSystemStartup!!!\n");
 
    /* Get the current CPU number */
    Cpu = KeNumberProcessors++; // FIXME
 
    /* LoaderBlock initialization for Cpu 0 */
    if (Cpu == 0)
    {
        /* Save the loader block */
        KeLoaderBlock = LoaderBlock;
 
        /* Prepare LoaderBlock, PCR, TSS with the P0 boot data */
        KiInitializeP0BootStructures(LoaderBlock);
    }
 
    /* Get Pcr from loader block */
    Pcr = CONTAINING_RECORD(LoaderBlock->Prcb, KIPCR, Prcb);
 
    /* Set the PRCB for this Processor */
    KiProcessorBlock[Cpu] = &Pcr->Prcb;
 
    /* Save the initial thread */
    InitialThread = (PKTHREAD)LoaderBlock->Thread;
 
    /* Set us as the current process */
    InitialThread->ApcState.Process = (PVOID)LoaderBlock->Process;
 
    /* Initialize the CPU features */
    KiInitializeCpu(Pcr);
 
    /* Initial setup for the boot CPU */
    if (Cpu == 0)
    {
        /* Set global feature bits */
        KeFeatureBits = (ULONG64)Pcr->Prcb.FeatureBitsHigh << 32 |
                        Pcr->Prcb.FeatureBits;
 
        /* Initialize the module list (ntos, hal, kdcom) */
        KiInitModuleList(LoaderBlock);
 
        /* Setup the IDT */
        KeInitExceptions();
 
         /* Initialize debugging system */
        KdInitSystem(0, KeLoaderBlock);
 
        /* Check for break-in */
        if (KdPollBreakIn()) DbgBreakPointWithStatus(DBG_STATUS_CONTROL_C);
    }
 
    DPRINT1("Pcr = %p, Gdt = %p, Idt = %p, Tss = %p\n",
           Pcr, Pcr->GdtBase, Pcr->IdtBase, Pcr->TssBase);
 
    /* Acquire lock */
    while (InterlockedBitTestAndSet64((PLONG64)&KiFreezeExecutionLock, 0))
    {
        /* Loop until lock is free */
        while ((*(volatile KSPIN_LOCK*)&KiFreezeExecutionLock) & 1);
    }
 
    /* Initialize the Processor with HAL */
    HalInitializeProcessor(Cpu, KeLoaderBlock);
 
    /* Set processor as active */
    KeActiveProcessors |= 1ULL << Cpu;
 
    /* Release lock */
    InterlockedAnd64((PLONG64)&KiFreezeExecutionLock, 0);
 
    /* Raise to HIGH_LEVEL */
    KfRaiseIrql(HIGH_LEVEL);
 
    /* Machine specific kernel initialization */
    if (Cpu == 0) KiInitializeKernelMachineDependent(&Pcr->Prcb, LoaderBlock);
 
    /* Initialize extended state management */
    KiInitializeXStateConfiguration(Cpu);
 
    /* Calculate the initial stack pointer */
    InitialStack = ALIGN_DOWN_BY(LoaderBlock->KernelStack - KeXStateLength, 64);
 
    /* Switch to new kernel stack and start kernel bootstrapping */
    KiSwitchToBootStack(InitialStack);
}