CD_INFO_ACK

Section: Communications Device Interface (CDI) (7)
Updated: 2008-10-31
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NAME

CD_INFO_ACK - information acknowledgment

SYNOPSIS

This primitive consists of one M_PROTO(9) or M_PCPROTO(9) message block structured as follows:

typedef struct {
    cd_ulong cd_primitive;
    cd_ulong cd_state;
    cd_ulong cd_max_sdu;
    cd_ulong cd_min_sdu;
    cd_ulong cd_class;
    cd_ulong cd_duplex;
    cd_ulong cd_output_style;
    cd_ulong cd_features;
    cd_ulong cd_addr_length;
    cd_ulong cd_ppa_style;
} cd_info_ack_t;

DESCRIPTION

This provider originated primitives acknowledges a previously issued CD_INFO_REQ(7) primitive, and provide protocol and limits information for the stream upon which the primitive is issued.

If the stream is in state CD_UNATTACHED, the information returned by CD_INFO_ACK might be different after a successful CD_ATTACH_REQ(7) than it was before the attach was completed. This is because the CD provider might not yet have all protocol information concerning the underlying communications device until after it has been attached to a specific Physical Point of Attachment.

Parameters

This primitive contains the following parameters:

cd_primitive

Indicates the primitives type.

cd_state

Indicates the state of the CDI provider. The cd_state can be one of the following values:

CD_UNATTACHED: No Physical Point of Attachment (PPA) is associated with the stream. Only Style 2 communications devices (streams that return CD_STYLE2 in the cd_ppa_style field) can exist in this state. CD_STYLE2 communications devices start in this state after open(2).
CD_UNUSABLE: PPA cannot be used.
CD_DISABLED: A Physical Point of Attachment (PPA) is associated with the stream, but the communications device is disabled. Style 1 communications devices (streams that return CD_STYLE1 in the cd_ppa_style filed) start in this state after open(2).
CD_ENABLE_PENDING: A CD_ENABLE_REQ(7) has been issued and is pending. The provider is waiting for enabling of the communications device to complete before confirmation with CD_ENABLE_CON(7) or error acknowledgement with CD_ERROR_ACK(7).
CD_ENABLED: The communications device is enabled and is awaiting use. Either the input or output must be active or allowed before data can be transferred.
CD_READ_ACTIVE: The input section is temporarily enabled and will be disabled after data arrives.
CD_INPUT_ALLOWED: The input section is permanently enabled.
CD_DISABLE_PENDING: A CD_DISABLE_REQ(7) has been issued and is pending. The provider is waiting for disabling of the communications device to complete before confirmation with CD_DISABLE_CON(7) or error acknowledgement with CD_ERROR_ACK(7).
CD_OUTPUT_ACTIVE: Output section active only.
CD_XRAY: Xray-ing another ppa.

cd_max_sdu

The maximum size of a Signalling Data Unit (SDU) in octets.

cd_min_sdu

The minimum size of a Signalling Data Unit (SDU) in octets.

cd_class

Indicates the class of the communications device. cd_class can be one of the following values:

CD_HDLC: Bit-synchronous.
CD_BISYNC: Character-synchronous.
CD_LAN: ISO 8802-3,4,5 local-area network MAC.
CD_NODEV: No device, PPA used for X-ray.

cd_duplex

Indicates full or half duplex operation. cd_duplex can be one of the following values:

CD_FULLDUPLEX: Full duplex; allow input supported.
CD_HALFDUPLEX: Half duplex; read write/read supported.

cd_output_style

Indicates the output style. cd_output_style can be one of the following values:

CD_UNACKEDOUTPUT: The communications device does not issue CD_UNITDATA_ACK(7) primitives.
CD_ACKEDOUTPUT: The communications device issues CD_UNITDATA_ACK(7) primitives in acknowledgement of CD_UNITDATA_REQ(7) primitives.
CD_PACEDOUTPUT: The communications device issues CD_UNITDATA_ACK(7) primitives only as output timing hints.

cd_features

Indicates the features supported by the communications device. cd_features can be a bitwise OR of the following flags:

CD_CANREAD: Read request supported on full duplex.
CD_CANDIAL: Dial information supported.
CD_AUTOALLOW: CD_INPUT_ALLOWED as soon as enabled.
CD_KEEPALIVE: Don't send off at CD_DISABLE_REQ(7). This is a Gcom extension.

cd_addr_length

The maximum size of an address for use with CD_UNITDATA_REQ(7), CD_UNITDATA_IND(7).

cd_ppa_style

Indicates the physical point of appearance style. cd_ppa_style can be one of the following values:

CD_STYLE1: The communications device is already attached to the physical point of appearance at open(2). The device starts in the CD_DISABLED state.
CD_STYLE2: The communications is not attached to a physical point of appearance at open(2), and must be attached with CD_ATTACH_REQ(7). The device starts in the CD_UNATTACHED state.

State

This primitive is valid in any state where a local acknowledgement (requiring response with a CD_OK_ACK(7)) is not pending, and only in response to a CD_INFO_REQ(7) primitive.

FILES

HISTORY

The Communications Device Interface first appeared in SVR 4[1].

CONFORMANCE

This interface conforms to CDI with Gcom extensions.

REFERENCES

[1]: SVR 4, UNIX® System V Release 4 Programmer's Manual, 1990, (Englewood Cliffs, New Jersey), AT&T UNIX System Laboratories, Inc., Prentice Hall.
[2]: Magic Garden, The Magic Garden Explained: The Internals of UNIX® System V Release 4 / An Open Systems Design, 1994, (Australia), B. Goodheart, J. Cox, Prentice Hall. [ISBN 0-13-098138-9]
[3]: Advanced Programming in the UNIX®Environment, 15th edition, December 1997, (Reading, Massachusetts), W. R. Stevens, Addison Wesley. [ISBN 0-201-56317-7]