2.4.ReactOS系统运行级别IRQL的切换

2.4.ReactOS系统运行级别IRQL的切换

2.4.ReactOS系统运行级别IRQL的切换

HalpLowerIrql函数

VOID
HalpLowerIrql(KIRQL NewIrql)
{
  if (NewIrql >= PROFILE_LEVEL)
    {
      KeGetPcr()->Irql = NewIrql;
      return;
    }
  HalpExecuteIrqs(NewIrql);
  if (NewIrql >= DISPATCH_LEVEL)
    {
      KeGetPcr()->Irql = NewIrql;
      return;
    }
  KeGetPcr()->Irql = DISPATCH_LEVEL;
  if (((PKIPCR)KeGetPcr())->HalReserved[HAL_DPC_REQUEST])
    {
      ((PKIPCR)KeGetPcr())->HalReserved[HAL_DPC_REQUEST] = FALSE;
      KiDispatchInterrupt();
    }
  KeGetPcr()->Irql = APC_LEVEL;
  if (NewIrql == APC_LEVEL)
    {
      return;
    }
  if (KeGetCurrentThread() != NULL && 
      KeGetCurrentThread()->ApcState.KernelApcPending)
    {
      KiDeliverApc(KernelMode, NULL, NULL);
    }
  KeGetPcr()->Irql = PASSIVE_LEVEL;
}

cpu的级别

//
// IRQL Levels
//
#define PASSIVE_LEVEL                           0x0
#define APC_LEVEL                               0x1
#define DISPATCH_LEVEL                          0x2
#define CLOCK2_LEVEL                            0x1C
#define HIGH_LEVEL                              0x1F