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Technical Reference: Kernel and Subsystems, Volume 2

CIO_START (Start Device) tokioctl Token-Ring Device Handler Operation


Note: This function is supported in AIX 5.1 and earlier only.

Initiates a session with the token-ring device.


The CIO_START tokioctl operation initiates a session with the token-ring device handler. If the start is the first on the port, the device handler initializes and opens the token-ring adapter. For each successful CIO_START call issued, there should be a corresponding CIO_HALT operation issued.

After the CIO_START operation has successfully completed, the adapter is ready to transmit and receive data. The caller can issue any valid token-ring operation. Once started, the adapter receives packets that match the token-ring adapter's (hardware) address or the address specified in the device-dependent structure (DDS) and broadcast packets. No group or functional address is specified when the adapter is started.

The caller notifies the device handler which network ID to use. The network ID corresponds to the destination service access point (DSAP) in the token-ring packet. The caller can issue multiple CIO_START operations. For each adapter the token-ring device handler can handle from 0 to the number of network IDs specified by the TOK_MAX_NETIDS label. This label is defined in the /usr/include/sys/tokuser.h file.

The CIO_START operation functions with a Token-Ring High Performance Network Adapter that has been correctly configured for use on a qualified network. Consult adapter specifications for more information on configuring the adapter and network qualifications.

session_blk Parameter Block

For the CIO_START operation, the arg parameter points to the session_blk structure. This structure is defined in the /usr/include/sys/comio.h file and contains the following fields:

Field Description
status Indicates the status of the CIO_START operation. Possible returned status values are:
netid Specifies the network ID the caller will use on the network. The network ID is placed in the least significant byte of the netid field. To request a medium-access control (MAC) frame session, the netid field should be set to the TOK_MAC_FRAME_NETID label. This value has a unique identifier in the most significant byte of the netid field. There can be only one MAC frame session per adapter.
The token-ring device handler does not allow the caller to specify itself as the wild card network ID.

Execution Environment

The CIO_START tokioctl operation can be called from the process environment only.

Return Values

EADDRINUSE Indicates the network ID is in use.
EINVAL Indicates a parameter is not valid.
ENETDOWN Indicates an unrecoverable hardware error.
ENOMSG Indicates an error.
ENOSPC Indicates the network ID table is full.

Related Information

The ddioctl (CIO_START) operation.

The CIO_GET_STAT tokioctl Token-Ring Device Handler Operation, CIO_HALT tokioctl Token-Ring Device Handler Operation.

The tokioctl entry point.

Common Communications Status and Exception Codes in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts.

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