[OpenVMS documentation]
[Site home] [Send comments] [Help with this site] [How to order documentation] [OpenVMS site] [Compaq site]
Updated: 11 December 1998

OpenVMS I/O User's Reference Manual

Previous Contents Index

8.7 Assigning a Channel to GKDRIVER

On VAX and Alpha systems, an application program assigns a channel to the generic SCSI class driver using the standard call to the $ASSIGN system service, as described in the OpenVMS System Services Reference Manual. The application program specifies a device name and a word to receive the channel number.

8.8 Issuing a $QIO Request to the Generic Class Driver

The format of the Queue I/O Request ($QIO) system service that initiates a request to the SCSI generic class driver is as follows. This explanation concentrates on the special elements of a $QIO request to the SCSI generic class driver. For a detailed description of the $QIO system service, see the OpenVMS System Services Reference Manual.

VAX MACRO Format 

$QIO  [efn] ,chan ,func ,iosb ,[astadr] ,[astprm] 
      ,p1 ,p2 [,p3] [,p4] [,p5] [,p6]

High-Level Language Format 

SYS$QIO ([efn] ,chan ,func ,iosb ,[astadr] ,[astprm] 
     ,p1 ,p2 [,p3] [,p4] [,p5] [,p6])

Arguments

chan

I/O channel assigned to the device to which the request is directed. The chan argument is a word value containing the number of the channel, as returned by the Assign I/O Channel ($ASSIGN) system service.

func

Longword value containing the IO$_DIAGNOSE function code. Only the IO$_DIAGNOSE function code is implemented in the generic SCSI class driver.

iosb

I/O status block. The iosb argument is required in a request to the generic SCSI class driver; it has the following format:

The status code provides the final status indicating the success or failure of the SCSI command. The SCSI status byte contains the status value returned from the target device, as defined in the ANSI SCSI specification. The transfer count field specifies the actual number of bytes transferred during the SCSI bus DATA IN or DATA OUT phase.

[efn]
[astadr] [astprm]

These arguments apply to $QIO system service completion. For an explanation of these arguments, see the OpenVMS System Services Reference Manual.

p1

Address of a generic SCSI descriptor of the following format:

p2

Length of the generic SCSI descriptor.

Descriptor Fields

opcode

Currently, the only supported opcode is 1, indicating a pass-through function. Other opcode values are reserved for future expansion.

flags

Bit map having the following format:

Bits in the flags bit map are defined as follows:
Field Definition
dir Direction of transfer.

If this bit is set, the target is expected at some time to enter the DATA IN phase to send data to the host. To facilitate this, the port driver maps the specified data buffer for write access.

If this bit is clear, the target is expected at some time to enter the DATA OUT phase to receive data from the host. To facilitate this, the port driver maps the specified data buffer for read access.

The generic SCSI class driver ignores the dir flag if either the SCSI data address or SCSI data length field of the generic SCSI descriptor is zero.

dis Enable disconnection.

If this bit is set, the target device is allowed to disconnect during the execution of the command.

If this bit is clear, the target cannot disconnect during the execution of the command.

Note that targets that hold on to the bus for long periods of time without disconnecting can adversely affect system performance. See Section 8.5.2 for additional information.

syn Enable synchronous mode.

If this bit is set, the port driver uses synchronous mode for data transfers, if both the host and target allow this mode of operation.

If this bit is clear, or synchronous mode is not supported by either the host or target, the port driver uses asynchronous mode for data transfers.

See Section 8.5.1 for additional information.

dpr Disable port retry.

If this bit is clear, the port driver retries, up to three times, any command that fails with a timeout, bus parity, or invalid phase transition error.

If this bit is set, the port driver does not retry commands for which it detects failure.

See Section 8.5.3 for additional information.

SCSI command address

Address of a buffer containing a SCSI command.

SCSI command length

Length of the SCSI command. The maximum length of the SCSI command is 128 bytes.

SCSI data address

Address of a data buffer associated with the SCSI command.

If the dir bit is set in the flags field, data is written into this buffer during the execution of the command. Otherwise, data is read from this buffer and sent to the target device.

If the SCSI command requires no data to be transferred, then the SCSI data address field should be clear.

SCSI data length

Length, in bytes, of the data buffer pointed to by the SCSI data address field. The maximum data buffer size is 65,535 bytes.

If the SCSI command requires no data to be transferred, then this field should be clear.

SCSI pad length

This field is used to accommodate SCSI device classes that require that the transfer length be specified in terms of a larger data unit than the count of bytes expressed in the SCSI data length field. If the total amount of data requested in the SCSI command does not match that specified in the SCSI data length field, this field must account for the difference.

For example, suppose an application program is using the generic class driver to read the first 2 bytes of a disk block. The length field in the SCSI READ command contains 1 (indicating one logical block, or 512 bytes), while the SCSI data length field contains a 2. The SCSI pad length field must contain the difference, 510 bytes.

For most transfers, this field should contain 0. Failure to initialize the SCSI pad length field properly causes port driver timeouts and SCSI bus resets.

phase change timeout

Maximum number of seconds for a target to change the SCSI bus phase or complete a data transfer. A value of 0 causes the SCSI port driver's default phase change timeout value of 4 seconds to be used.

See Section 8.5.4 for additional information.

disconnect timeout

Maximum number of seconds for a target to reselect the initiator to proceed with a disconnected I/O transfer. A value of 0 causes the SCSI port driver's default disconnect timeout value of 4 seconds to be used.

See Section 8.5.4 for additional information.

8.9 Generic SCSI Class Driver Device Information

A call to the Get Device/Volume Information ($GETDVI) system service returns the following information for any device serviced by the generic SCSI class driver. (See the description of the $GETDVI system service in the OpenVMS System Services Reference Manual.)

$GETDVI returns the following device characteristics when you specify the item code DVI$_DEVCHAR:
DEV$M_AVL Available device
DEV$M_IDV Input device
DEV$M_ODV Output device
DEV$M_SHR Shareable device
DEV$M_RND Random-access device

DVI$DEVCLASS returns the device class, which is DC$_MISC; DVI$DEVTYPE returns the device type, which is DT$_GENERIC_SCSI.

8.10 Call a Generic SCSI Class Driver

Example 8-1 is an application that uses the generic SCSI class driver to send a SCSI INQUIRY command to a device.

Example 8-1 Generic SCSI Class Driver Call Example 

/* 
GKTEST.C 
 
This program uses the SCSI generic class driver to send an inquiry command 
to a device on the SCSI bus. 
 
*/ 
 
#include ctype 
 
/* Define the descriptor used to pass the SCSI information to GKDRIVER */ 
 
#define OPCODE 0 
#define FLAGS 1 
#define COMMAND_ADDRESS 2 
#define COMMAND_LENGTH 3 
#define DATA_ADDRESS 4 
#define DATA_LENGTH 5 
#define PAD_LENGTH 6 
#define PHASE_TIMEOUT 7 
#define DISCONNECT_TIMEOUT 8 
 
#define FLAGS_READ 1 
#define FLAGS_DISCONNECT 2 
 
#define GK_EFN 1 
 
#define SCSI_STATUS_MASK 0X3E 
 
#define INQUIRY_OPCODE 0x12 
#define INQUIRY_DATA_LENGTH 0x30 
 
globalvalue 
        IO$_DIAGNOSE; 
 
short 
        gk_chan, 
        transfer_length; 
 
int 
        i, 
        status, 
        gk_device_desc[2], 
        gk_iosb[2], 
        gk_desc[15]; 
 
char 
        scsi_status, 
        inquiry_command[6] = {INQUIRY_OPCODE, 0, 0, 0, INQUIRY_DATA_LENGTH, 0}, 
        inquiry_data[INQUIRY_DATA_LENGTH], 
        gk_device[] = {"GKA0"}; 
 
main () 
{ 
 
/* Assign a channel to GKA0 */ 
 
        gk_device_desc[0] = 4; 
        gk_device_desc[1] = &gk_device[0]; 
        status = sys$assign (&gk_device_desc[0], &gk_chan, 0, 0); 
        if (!(status & 1)) sys$exit (status); 
 
/* Set up the descriptor with the SCSI information to be sent to the target */ 
 
        gk_desc[OPCODE] = 1; 
        gk_desc[FLAGS] = FLAGS_READ + FLAGS_DISCONNECT; 
        gk_desc[COMMAND_ADDRESS] = &inquiry_command[0]; 
        gk_desc[COMMAND_LENGTH] = 6; 
        gk_desc[DATA_ADDRESS] = &inquiry_data[0]; 
        gk_desc[DATA_LENGTH] = INQUIRY_DATA_LENGTH; 
        gk_desc[PAD_LENGTH] = 0; 
        gk_desc[PHASE_TIMEOUT] = 0; 
        gk_desc[DISCONNECT_TIMEOUT] = 0; 
        for (i=9; i<15; i++) gk_desc[i] = 0;    /* Clear reserved fields */ 
 
/* Issue the QIO to send the inquiry command and receive the inquiry data */ 
 
        status = sys$qiow (GK_EFN, gk_chan, IO$_DIAGNOSE, gk_iosb, 0, 0, 
                           &gk_desc[0], 15*4, 0, 0, 0, 0); 
 
/* Check the various returned status values */ 
 
        if (!(status & 1)) sys$exit (status); 
        if (!(gk_iosb[0] & 1)) sys$exit (gk_iosb[0] & 0xffff); 
        scsi_status = (gk_iosb[1] >> 24) & SCSI_STATUS_MASK; 
        if (scsi_status) { 
                printf ("Bad SCSI status returned: %02.2x\n", scsi_status); 
                sys$exit (1); 
        } 
 
/* The command succeeded. Display the SCSI data returned from the target */ 
 
        transfer_length = gk_iosb[0] >> 16; 
        printf ("SCSI inquiry data returned: "); 
        for (i=0; i<transfer_length; i++) { 
                if (isprint (inquiry_data[i])) 
                        printf ("%c", inquiry_data[i]); 
                else 
                        printf ("."); 
        } 
        printf ("\n"); 
}

Chapter 9
Local Area Network (LAN) Device Drivers

This chapter has been updated for OpenVMS Version 7.2.

This chapter describes the QIO interface of local area network (LAN) drivers that control the LAN devices.

In addition to the QIO interface, the OpenVMS operating system supports another interface into LAN drivers. The VMS Communications Interface (VCI) provides a privileged interface that is optimized for network transfers.

9.1 Local Area Network (LAN) Terminology

The following is a list of terms relevant to local area networks:

9.2 Supported Communication Devices

Section 9.2.1 and Section 9.2.2 show the communication devices supported on the OpenVMS operating system.

9.2.1 OpenVMS VAX Lan Devices

On VAX systems, Table 9-1 lists the supported devices.

Table 9-1 Supported OpenVMS VAX Systems LAN Devices
Medium Bus Device Device Name DECnet Name Device Type Version
CSMA/CD XMI DEMNA EXc0 MNA DT$_EX_DEMNA V5.3
CSMA/CD Local SGEC EZc0 ISA DT$_EZ_SGEC V5.3
CSMA/CD Local LANCE ESc0 SVA DT$_ES_LANCE V4.4
CSMA/CD TurboChannel PMAD ECc0 MXE DT$_EC_PMAD V5.5-2HW
CSMA/CD TurboChannel DELTA ECc0 MXE DT$_EC_PMAD V5.5-2HW
CSMA/CD QBUS DESQA ESc0 SVA DT$_ES_LANCE V5.0
CSMA/CD QBUS DELQA XQc0 QNA DT$_XQ_DELOA V5.0
CSMA/CD QBUS DEQTA XQc0 QNA DT$_XQ_DEQTA V5.3
CSMA/CD QBUS DEQNA XQc0 QNA DT$_DEQNA V4.0
CSMA/CD QBUS KFE52 EFc0 KFE DT$_FT_NI V5.4
CSMA/CD UNIBUS DEUNA XEc0 UNA DT$_DEUNA V4.0
CSMA/CD UNIBUS DELUA XEc0 UNA DT$_DELUA V4.0
CSMA/CD BI DEBNA ETc0 BNA DT$_ET_DEBNA V4.4
CSMA/CD BI DEBNK ETc0 BNA DT$_ET_DEBNA V4.4
CSMA/CD BI DEBNT ETc0 BNA DT$_ET_DEBNA V4.4
CSMA/CD BI DEBNI ETc0 BNA DT$_ET_DEBNI V5.2
             
FDDI XMI DEMFA FXc0 MFA DT$_FX_DEMFA V5.4-3
FDDI TurboChannel DEFZA FCc0 FZA DT$_FC_DEFZA V5.5-2HW
FDDI TurboChannel DEFTA FCc0 FZA DT$_FC_DEFTA V6.0
FDDI QBUS DEFQA FQc0 FQA DT$_FQ_DEFQA V6.1

Note
The DEQTA device is also known as the DELQA-YM. Also note that the device name is the name of the template device which is used by applications to identify the LAN device. The "c" in the device name indicates the controller letter, for example, A, B, and so on.

9.2.2 OpenVMS Alpha Lan Devices

On Alpha systems, Table 9-2 lists the supported devices.

Table 9-2 Supported OpenVMS Alpha LAN Devices
Medium Bus Device Device Name DECnet Name Device Type Version
CSMA/CD XMI DEMNA EXc0 MNA DT$_EX_DEMNA V1.0
CSMA/CD CBUS TGEC EZc0 ISA DT$_EZ_TGEC V1.0
CSMA/CD TurboChannel COREIO ESc0 SVA DT$_ES_LANCE V1.0
CSMA/CD TurboChannel PMAD ECc0 MXE DT$_EC_PMAD V1.0
CSMA/CD TurboChannel DELTA ECc0 MXE DT$_EY_NITC2 V6.1
CSMA/CD EISA DE422 ERc0 ERA DT$_ER_DE422 V1.5
CSMA/CD EISA DE425 ERc0 ETA DT$_ER_TULILP V6.1
CSMA/CD ISA DE200 ERc0 ERA DT$_ER_LANCE V6.1
CSMA/CD ISA DE201 ERc0 ERA DT$_ER_LANCE V6.1
CSMA/CD ISA DE202 ERc0 ERA DT$_ER_LANCE V6.1
CSMA/CD ISA DE203 ERc0 ERA DT$_ER_LEMAC V6.2
CSMA/CD ISA DE204 ERc0 ERA DT$_ER_LEMAC V6.2
CSMA/CD ISA DE205 ERc0 ERA DT$_ER_LEMAC V6.2
CSMA/CD PCI Tulip EWc0 EWA DT$_EW_TULIP V6.1
CSMA/CD PCI DE434 EWc0 EWA DT$_EW_DE435 V6.1
CSMA/CD PCI DE435 EWc0 EWA DT$_EW_DE435 V6.1
CSMA/CD PCI DE436 EWc0 EWA DT$_EW_DE435 V6.1
CSMA/CD PCI DE450 EWc0 EWA DT$_EW_DE450 V6.2
CSMA/CD PCI DE500-XA EWc0 EWA DT$_EW_DE500 V6.2
CSMA/CD PCI DE500-AA EWC0 EWA DT$_EW_DE500 V6.2
CSMA/CD PCI DE500-BA EWc0 EWA DT$_EW_DE500 V6.2
CSMA/CD PCI DE504-BA EWc0 EWA DT$_EW_DE504 V7.1-1H1
CSMA/CD PCI DE500-FA EWc0 EWA DT$_EW_DE500 V7.1
CSMA/CD PCMCIA 3COM 3C589B EOc0 CEC DT$_EO_3C589 V6.2-1H2
CSMA/CD PCI DEGPA-SA EWc0 EWA DT$_EW_DEGPA V7.1-2
             
FDDI XMI DEMFA FXc0 MFA DT$_FX_DEMFA V1.0
FDDI FutureBus+ DEFAA FAc0 FAA DT$_FA_DEFAA V1.5
FDDI TurboChannel DEFZA FCc0 FZA DT$_FC_DEFZA V1.0
FDDI TurboChannel DEFTA FCc0 FZA DT$_FC_DEFTA V1.5
FDDI EISA DEFEA FRc0 FEA DT$_FR_DEFEA V1.5-1H1
FDDI PCI DEFPA FWc0 FPA DT$_FW_DEFPA V6.2
             
TokenRing TurboChannel DETRA ICc0 TRA DT$_IC_DETRA V6.1
TokenRing EISA DW300 IRc0 TRE DT$_IR_DW300 V6.1
TokenRing ISA DW110 IRc0 TRE DT$_IR_DW300 V6.2
TokenRing PCI PBXNP-AA IWc0 TRE DT$_IW_TI380PCI V6.2-1H1
TokenRing PCI PBXNP-DA IWc0 TRE DT$_IW_RACORE V7.1-1H1
             
ATM TurboChannel DGLTA HCc0
/ELc0
ELA 		DT$_HC_OTTO V6.2
ATM PCI DGLPB HWc0
/ELc0
ELA 		DT$_HW_OTTO V7.1-1H1
ATM PCI DGLPA HWc0
/ELc0
ELA 		DT$_HW_METEOR V7.1-2

Previous Next Contents Index

[Site home] [Send comments] [Help with this site] [How to order documentation] [OpenVMS site] [Compaq site]
[OpenVMS documentation]

Copyright © Compaq Computer Corporation 1998. All rights reserved.

Legal
6136PRO_028.HTML