DosSMRegisterDD

Allows a device driver to register itself with the Session Manager.

DosSMRegisterDD

(RegisterData)

RegisterData (PREGISTERDATA) - input

Address of the structure containing the RegisterData necessary for this call.

Length (USHORT)

Length of the data structure in bytes including Length itself. Length is 8 for OS/2 version 1.2.
Notification (USHORT)
Bit map that informs the session manager when to issue the notification IOCTL to the device driver. The bits of this word are defined as follows:

Bit

Description
15-4
Reserved and must be set to zero.
3
Session termination notification. Action = 8
2
Post-Session restore notification. Action = 4
1
Post-Session save notification. Action = 2
0
Pre-Session save notification. Action = 1
Action is the unsigned integer in the Action field of the notification IOCTL. This tells the device driver what is happening. Notice that the integers correspond to bits 0 to 3 being set.
DDName (ULONG)
Address of the device name, as an ASCIIZ string (ie. SCREEN$, KBD$, etc.).
rc (USHORT) - return
Return code descriptions are:

418

ERROR_SMG_INVALID_CALL
461
ERROR_SMG_INVALID_DATA_LENGTH
515
ERROR_SMG_TOO_MANY_DDS
516
ERROR_SMG_INVALID_NOTIFICATION
Remarks

The Session Manger calls the registered device driver during a session switch, based on the specific form of notifications required.

The notification IOCTL passed to the device driver has the following format:

Size

Definition
WORD
DevIOCtl packet length, including the length itself
WORD
Screen switch notification type
WORD
Incoming session number
WORD
Outgoing session number.

The device driver passes a bit map that informs the session manager when the device driver needs to be called. The possible phases are:

Before a session save After a session save (before a restore)
After a session restore
After a session termination.


The device drivers must issue this API only during their initialization phase. After the session manager has been initialized, it rejects all further calls to this API, returning ERROR_SMG_INVALID_CALL.

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