Receiving a Physical COM Port from the Windows VCDLast reviewed: April 12, 1995Article ID: Q76564 |
The information in this article applies to:
SUMMARYIn the enhanced mode of the Microsoft Windows graphical environment, the virtual communications device (VCD) assigns a physical communications (COM) port to a virtual machine (VM) only when certain events occur. The text below lists these events.
MORE INFORMATIONIn Windows enhanced mode, the VCD virtualizes and serializes the ownership of physical COM ports. When a program running in a VM directly accesses one of the I/O ports of a COM port (for example, COM1 corresponds to I/O ports 0x3F8 through 0x3FE), that VM may not necessarily own the physical port. The VM communicates with a virtual COM port until the VCD assigns a physical port. Seven conditions that cause the VCD to assign a physical COM port to a particular VM are:
VCD_Attach called by: VCD_Set_OwnerVCD_Detach called by: VCD_Set_OwnerVCD_Set_Owner called by: VCD_Assign VCD_Set_Port_Global VCD_PM_Acquire_Port VCD_PM_Free_Port VCD_Set_Focus VCD_Set_Owner_Event VCD_Detach_If_OwnerVCD_Assign called by: VCD_PM_Steal_Port VCD_Cant_Virtualize VCD_MaskVCD_PM_Steal_Port called by: Comm Driver KickTx/StealPortVCD_Cant_Virtualize called by: VCD_Virt_In_Out_RxTxB (Condition 1) VCD_Virt_In_LSR (Condition 2) VCD_Virt_In_MSR (Condition 3) VCD_Virt_Out_MCR (Condition 4)VCD_Mask called by: VCD_handler (VPICD Mask_Change_Proc) (Condition 5)VCD_PM_Acquire_Port called by: Comm Driver GetCOMport386 (Condition 7)VCD_PM_Free_Port called by: Comm Driver ReleaseCOMport386VCD_Set_Owner_Event called by: VCD_Int (Condition 6)VCD_Detach_If_Owner called by: VCD_Destroy_VM |
Additional reference words: 3.00 3.10 DDKCOMM
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