Technical data

SDA Description
caused the bugcheck is located on the stack. See Section 8.2 for information
about how to proceed for several types of bugchecks.
3. Once you have found the address of the instruction that caused the bugcheck,
you need to find the module in which the failing instruction resides. Use the
SHOW DEVICE command to determine whether the instruction is part of a
device driver.
• If the module is not part of a driver, examine the linker’s map of
the module or modules you are debugging to determine whether the
instruction that caused the bugcheck is in your programs.
• If the module is not within a driver or other code supplied by Compaq,
perform the following steps:
a. Issue the following SDA command:
SDA> SHOW EXECUTIVE
This command shows the location and size of each of the loadable
images that make up the executive.
b. Compare the suspected address with the addresses of the system
images.
c. If the address is within one of the images, issue the following
command:
SDA> READ/EXECUTIVE SYS$LOADABLE_IMAGES:
This command loads the symbols that define locations within the
loadable portion of the executive. (READ/EXECUTIVE is the default
display.)
d. Examine the failing address by issuing the following command:
SDA> EXAMINE @PC
SDA then displays the address in the PC as an offset from the nearest
global symbol. This symbol might be the module’s starting address,
although it is possible that the code you are examining might not be
in the module whose name is displayed.
4. To determine the general cause of the system failure, examine the code that
signaled the bugcheck.
8.2 Fatal Bugcheck Conditions
Several conditions result in a bugcheck. Normally, these occasions are rare.
When they do occur, it is likely that they are in the nature of a fatal exception
or an illegal page fault occurring within privileged code. This section describes
the symptoms of these bugchecks. A discussion of other exceptions and condition
handling in general appears in the OpenVMS System Services Reference Manual.
8.2.1 Fatal Exceptions
An exception is fatal when it occurs while the following conditions exist:
• The process is using the interrupt stack.
• The process is executing above IPL 2 (IPL$_ASTDEL).
• The process is executing in a privileged (kernel or executive) processor access
mode and has not declared a condition handler to deal with the exception.
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