HP OpenVMS Systems

DBG$DYN_BEGIN

Notifies the HP DCPI daemon that a process will be executing dynamic sections of code.

Format

DBG$DYN_BEGIN facility-id, number-of-bytes-in-code-section, code-section-base-address, number-of-bytes-in-dst-section, dst-section-base-address, context

Returns

OpenVMS usage:	cond value
type:	longword (unsigned)
access:	write only
mechanism:	by value

Arguments

facility-id

OpenVMS usage:	char_string
type:	character string
access:	read only
mechanism:	by descriptor

The facility-id argument is used in naming the image file that the DCPI daemon creates.

number-of-bytes-in-code-section

OpenVMS usage:	quadword_signed
type:	quadword (signed)
access:	read only
mechanism:	by value

The number-of-bytes-in-code-section argument specifies the size, in bytes, of the section of virtual memory where dynamic code will be contained and executed.

code-section-base-address

OpenVMS usage:	address
type:	quadword (unsigned)
access:	read only
mechanism:	by value

The code-section-base-address argument specifies the address of the first contiguous block of bytes allocated for the creation of DST records.

number-of-bytes-in-dst-section

OpenVMS usage:	quadword_signed
type:	quadword (signed)
access:	read only
mechanism:	by value

The number-of-bytes-in-dst-section argument specifies the size, in bytes, of the section of virtual memory where DST records will be contained.

dst-section-base-address

OpenVMS usage:	address
type:	quadword (unsigned)
access:	read only
mechanism:	by value

The dst-section-base-address argument specifies the first address of the contiguous block of bytes allocated for the creation of DST records.

context

OpenVMS usage:	quadword
type:	quadword (unsigned)
access:	read write
mechanism:	by reference

The context argument specifies the unique identifier assigned by DBG$DYN_BEGIN to the caller.

Description

The Begin Dynamic Code Execution routine notifies a running DCPI daemon that the calling process will be creating and executing code dynamically. The daemon will expect that all dynamically created code segments and DST records will fall within the address ranges described by their respective number-of-bytes and code-section-base-address arguments. When this routine is called, the daemon will create a portion of the pseudo-image file describing these sections. The name of this file will be determined by DCPI daemon and will contain the facility-id  string, the pid of the process, and the caller’s unique context number. The context number is assigned to the caller by the DBG$DYN_BEGIN routine. It is used to differentiate between multiple callers of DBG$DYN_BEGIN. This identifier must be provided to subsequent DBG$DYN_ADD and DBG$DYN_END calls.

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Condition Values Returned

SS$_NORMAL	The routine successfully completed.
SS$_BADPARAM	Routine was provided an invalid parameter.
Other	If this routine does not complete successfully, it returns the status of the call it made that failed.

Example

See an example of the interaction between DCPI and an application that executes code dynamically.