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On VAX 8530, 8550, 8600, 8650, 8810 (8700), 8820, 8820-N (8800), 8830, 8840, VAX-11/780, or VAX-11/785 computers, enter the following commands at the console terminal to request the interrupt:
$ [Ctrl/P] >>> HALT >>> D/I 14 E >>> C |
For a VAX 9000 computer, enter the following commands at the console terminal to request the interrupt:
$ [Ctrl/P] >>> HALT/CPU=ALL >>> D/I 14 E >>> C/CPU=ALL |
For a VAX 6000 series, 8200, 8250, 8300, 8350, VAX-11/730, or a VAX-11/750 computer, enter the following commands:
$ [Ctrl/P] >>> D/I 14 E >>> C |
For a VAXstation 3520 or 3540 computer, perform the following steps:
>>> D/I 14 E >>> C/ALL |
For a VAXft-3000, VAXft-410, VAXft-610, or VAXft-612 computer, enter the following commands at the console terminal to request the interrupt:
$ [Break] or [F5] >>> HALT >>> D/I 14 E >>> CONT >>> PIO |
For a VAX 7000 or VAX 10000 series computer, enter the following commands at the console terminal to request the interrupt. If you are operating in secure mode, first set the keyswitch to ENABLE before entering these commands.
$ [Ctrl/P] >>> D IPR:14 E >>> CONT |
For a VAXstation 2000, MicroVAX 2000, MicroVAX 3300/3400 series, MicroVAX or VAXstation 3500/3600 series, MicroVAX 3800/3900 series, VAX 4000 series, or MicroVAX II computer, perform the following steps:
>>> D/I 14 E >>> C |
For an alternative method of accessing OpenVMS through a lower priority
interrupt, see the HP OpenVMS System Manager's Manual.
1.8.2 Requesting Interrupts on Alpha
On Alpha systems, perform the following steps to request an interrupt:
^P |
>>> DEP SIRR E |
>>> CONT |
The process should enter XDELTA as soon as IPL drops to 14.
The following message is displayed:
Brk 0 at address address! instruction |
At this point, the exception frame is on the stack. The saved PC/PS in
the exception frame tells you where you were in the program when you
requested the interrupt.
1.8.3 Requesting Interrupts on I64
To request an interrupt on I64, type CTRL/P on the console terminal. Note that XDELTA must have been loaded previously.
When you press CTRL/P, the system is halted at the current PC and at
the current IPL. The system must be executing below IPL 8. When the
system reaches this state, execution is suspended at the PC that was
executing at the time of the interrupt.
1.9 Accessing the Initial Breakpoint
When debugging a program, you can set a breakpoint in the code so that XDELTA gains control of program execution.
To set a breakpoint, place a call to the system routine INI$BRK in the source code.
On systems that are booted with XDELTA, the INI$BRK routine executes a breakpoint instruction. On systems that are not booted with XDELTA, INI$BRK is effectively a NOP instruction.
You can use the INI$BRK routine as a debugging tool, placing calls to this routine in any part of the source code you want to debug.
On VAX, the instruction following the breakpoint is RSB. After the break is taken, the return address (the address in the program to which control returns when you proceed from the breakpoint) is on the top of the stack.
The following command calls the INI$BRK system routine to reach the breakpoint:
JSB G^INI$BRK |
On Alpha, the instruction following the breakpoint is JSR R31,(R26). After the break is taken, the return address (the address in the program to which control returns when you proceed from the breakpoint) is in R26.
On I64, simply step until you reach a br.ret instruction.
The following C routine calls the INI$BRK system routine to reach the breakpoint:
extern void ini$brk(void);
main()
{
ini$brk();
}
|
On VAX, when XDELTA reaches one of its breakpoints, it displays the following message:
1 BRK AT nnnnnnnn address/instruction operands |
On I64 and Alpha, when XDELTA reaches one of its breakpoints, it displays the following message:
BRK 1 AT nnnnnnnn address!instruction operands |
On multiprocessor computers, the XDELTA breakpoint is taken on the processor upon which the XDELTA software interrupt was requested, which is generally the primary processor.
At this point, XDELTA is waiting for input. If you want to proceed with program execution, enter the ;P command. If you want to do step-by-step program execution, enter the S command. If you know where you have set breakpoints, examine them using the ;B command. You can also set additional breakpoints or modify existing ones.
If you entered the ;P command to proceed with program execution and the system halts with a fatal bugcheck, the system prints the bugcheck information on the console terminal. Bugcheck information consists of the following:
The contents of the program counter (PC) and the stack indicate where
the failure was detected. Then, if the system parameter BUGREBOOT was
set to 0, XDELTA issues a prompt. You can examine the system's state
further by entering XDELTA commands.
1.11 Exiting from XDELTA
XDELTA remains in memory with the operating system until you reboot without it.
This chapter describes how to form the symbolic expressions used as
arguments to many DELTA and XDELTA commands.
2.1 Symbols Supplied by DELTA and XDELTA
DELTA and XDELTA define symbols that are useful in forming expressions and referring to registers.
| Symbol | Description |
|---|---|
| . | The address of the current location. The value of this symbol is set by the Open Location and Display Contents (/), Open Location and Display Instruction (!), and the Open Location and Display Indirect (TAB) commands. |
| ARn | Application register n where n can range from 0 to 127 (decimal). Also see the P(ipr) symbol description. |
| BRn | Branch register n where n can range from 0 to 7. |
| CRn | Control register n where n can range from 0 to 127 (decimal). See also the P(ipr) symbol description. |
| FPn | Floating point register n, where n can range from 0 to 127 (decimal). |
| FPSR | The floating point status register. |
| G | ^XFFFFFFFF80000000, the prefix for system space addresses. |
| H | ^X7FFE0000, the prefix for addresses in the control region (P1 space). H2E, for example, is equivalent to ^X7FFE002E. |
| P(ipr) |
The OpenVMS I64 software implementation of an Alpha internal processor
register whose name is
ipr. See the Alpha Architecture Reference Manual for the names and descriptions of
these processor registers. Not all Alpha internal processor registers
are implemented on OpenVMS I64.
This syntax is also used to refer to Intel Itanium application and control registers using meaningful names, where ipr is the name of the Intel Itanium register. For example, you can refer to Intel Itanium register CR20 using either of the following: P(IFA) See the Intel® IA-64 Architecture Software Developer's Manual, Volume 2: IA-64 System Architecture manual for the names of the application and control registers. |
| PC | The OpenVMS I64 software implementation of a program counter register, formed by the union of the IP (instruction bundle pointer) and the slot offset (PSR.ri). |
| pid:Rn | General register n in the process specified by process ID pid. |
| PS | The processor status register. |
| Pn | Predicate register n where n can range from 0 to 63 (decimal). |
| Q | The last value displayed. The value of Q is set by every command that causes DELTA or XDELTA to display the contents of memory or the value of an expression. |
| Rn | General register n where n can range from 0 to 127 (decimal). |
| Xn |
Base register
n, where
n can range from 0 to 15 (decimal). These registers are used
for storing values, most often the base addresses of data structures in
memory.
For XDELTA only, X14 and X15 contain the addresses of two command strings that XDELTA stores in memory. See the Execute Command String (;E) command for more information. For XDELTA only, registers X4 and X5 contain specific addresses. X4 contains the address of the location that contains the PCB address of the current process on the current processor. The address that X4 contains is that of the per-CPU database for the current processor. X5 contains SCH$GL_PCBVEC, the symbolic address of the start of the PCB vector, and the list of PCB slots. |
| Symbol | Description |
|---|---|
| . | The address of the current location. The value of this symbol is set by the Open Location and Display Contents (/), Open Location and Display Instruction (!), and the Open Location and Display Indirect (TAB) commands. |
| FPn | Floating point register n, where n can range from 0 to 31 (decimal). |
| FPCR | The floating point control register. |
| G | ^XFFFFFFFF80000000, the prefix for system space addresses. |
| H | ^X7FFE0000, the prefix for addresses in the control region (P1 space). H2E, for example, is equivalent to ^X7FFE002E. |
| PC | The program counter register. |
| pid:PC | The program counter in the process specified by process ID pid. |
| PS | The processor status register. |
| Q | The last value displayed. The value of Q is set by every command that causes DELTA or XDELTA to display the contents of memory or the value of an expression. |
| pid:Rn | General register n in the process specified by process ID pid. |
| Rn | General register n, where n can range from 0 to 31 (decimal). |
| Xn |
Base register
n, where
n can range from 0 to 15 (decimal). These registers are used
for storing values, most often the base addresses of data structures in
memory.
For XDELTA only, X14 and X15 contain the addresses of two command strings that XDELTA stores in memory. See the Execute Command String (;E) command for more information. For XDELTA only, registers X4 and X5 contain specific addresses. X4 contains the address of the location that contains the PCB address of the current process on the current processor. The address that X4 contains is that of the per-CPU database for the current processor. X5 contains SCH$GL_PCBVEC, the symbolic address of the start of the PCB vector, and the list of PCB slots. |
| Symbol | Description |
|---|---|
| . | The address of the current location. The value of this symbol is set by the Open Location and Display Contents (/), Open Location and Display Instruction (!), and the Open Location and Display Indirect (TAB) commands. |
| G | ^X80000000, the prefix for system space addresses. G2E, for example, is equivalent to ^X8000002E. |
| H | ^X7FFE0000, the prefix for addresses in the control region (P1 space). H2E, for example, is equivalent to ^X7FFE002E. |
| Pn | The internal processor register at processor address n, where n can range from 0 to 3F (hexadecimal). See the VAX Architecture Reference Manual for a description of these processor registers. |
| Q | The last value displayed. The value of Q is set by every command that causes DELTA or XDELTA to display the contents of memory or the value of an expression. |
| Rn | General register n, where n can range from 0 to F (hexadecimal). RF+4 is the processor status longword (PSL), RE is the stack pointer, and RF is the program counter (PC). |
| Xn |
Base register
n, where
n can range from 0 to F (hexadecimal). These registers are
used for storing values, most often the base addresses of data
structures in memory.
For XDELTA only, XE and XF contain the addresses of two command strings that XDELTA stores in memory. See the Execute Command String (;E) command for more information. For XDELTA only, registers X4 and X5 contain specific addresses. X4 contains the address of the location that contains the PCB address of the current process on the current processor. The address that X4 contains is that of the per-CPU database for the current processor. X5 contains SCH$GL_PCBVEC, the symbolic address of the start of the PCB vector, and the list of PCB slots. |
On OpenVMS Alpha, floating point registers can be accessed from DELTA and from XDELTA but only if floating point arithmetic is enabled in the current process. On OpenVMS I64, floating point registers FP6 through FP11 are always available. The other floating point registers are available if floating point arithmetic is enabled in the current process.
DELTA runs in the context of a process. On OpenVMS Alpha, access to floating-point registers is enabled as soon as the first floating point instruction in the code being examined is executed. Access is disabled as soon as that image completes execution. On OpenVMS I64, floating-point registers are always available to DELTA.
Table Table 2-4 shows these relationships:
| Alpha | I64 | |
|---|---|---|
| XDELTA | No access | FP6---FP11 |
| DELTA | FPn if FP access is enabled | Always available |
When the system enters XDELTA, it may not be obvious which process is
the current process. If the current process happens to have floating
point enabled (because a floating point instruction has executed and
the image containing the floating point instruction is still
executing), then you can access the floating point registers.
Otherwise, you cannot. XDELTA checks the FEN (floating point enable)
IPR (internal processor register) to see whether it needs to provide
access to floating point registers.
2.3 Forming Numeric Expressions
Expressions are combinations of numbers, symbols that have numeric values, and arithmetic operators.
On all platforms, DELTA and XDELTA store and display all numbers in hexadecimal. They also interpret all numbers as hexadecimal.
Expressions are formed using regular (infix) notation. Both DELTA and XDELTA ignore operators that trail the expression. The following is a typical expression (in hexadecimal):
G4A32+24 |
DELTA and XDELTA recognize five binary arithmetic operators, one of which also acts as a unary operator. They are listed in Table 2-5.
| Operator | Action |
|---|---|
| + or SPACE | Addition |
| - | Subtraction when used as a binary operator, or negation when used as a unary operator |
| * | Multiplication |
| % | Division |
| @ | Arithmetic shift |
The following example shows the arguments required by the arithmetic-shift operator:
|
n@j |
In this example, n is the number to be shifted, and j is the number of bits to shift it. If j is positive, n is shifted to the left; if j is negative, n is shifted to the right. Argument j must be less than 2016 and greater than -2016. Bits shifted beyond the limit of the longword are lost; therefore, the result must fit into a longword.
Do not enter unnecessary spaces, as DELTA/XDELTA treats the space as an additional operator. |
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