Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (H-K)
Guardian Procedure Calls Reference Manual—522629-013
7-32
HIST_INIT_ Procedure
A subsequent call to HIST_FORMAT_ returns context for that
location. The address must point to a code location, but that
location can contain TNS instructions or RISC instructions. To find
out what is at a TNS address, you must first convert the TNS
address into a RISC address. See the
System Description Manual
for details on address translation.
10 HO_Init_FuncPtr
uses a 32-bit function pointer for the context. In the TNS/E
environment, the function pointer is an Official Function Descriptor
(OFD); a two-element array consisting of a 64-bit code address
and a 64-bit GP address. The OFD is passed to the HIST_INIT_
procedure in the context parameter. A subsequent call to
HIST_FORMAT_ returns the context for the code address that was
passed through the OFD. In the TNS/R environment, the function
pointer is a 32-bit native address that is also passed to the
HIST_INIT_ procedure in the context parameter. When you
specify the HO_Init_FuncPtr option in the TNS/R environment, it is
equivalent to specifying the HO_Init_Address option. For more
information on the HO_Init_Address option, see the description
above. Note that a subsequent call to HIST_FORMAT_ always
returns the correct context for the code location. This is true
regardless of whether an OFD (TNS/E environment) or a 32-bit
native address (TNS/R environment) is passed to the HIST_INIT_
procedure in the context parameter specified with the
HO_Init_FuncPtr option. The HO_Init_FuncPtr option is not
supported from the TNS environment.
In addition, the displayed context is affected when any combination of the following
bits are set to 1:
<11> HO_NoSuppress
enables the display of transition frames, including the shells by
which TNS code calls native procedures, the system procedure
that calls a signal handler, and some transitions within low-level
system software. By default, transition frames are not displayed.
<10> HO_ShowProtected
enables the display of protected context when a signal is
generated within protected code. If a signal is generated within
protected code, such as in a procedure running privileged, the
context at that site is preserved in the uContext structure passed
to the signal handler, but it is not displayed unless this option is
set.