HP 64783A, Руководство пользователя

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changed after the guarded access occurred. In this case, the present address in the
program counter may map to proper physical memory.
If the present program counter address does not translate to an address in guarded
physical memory, the access to guarded memory may have been caused when your
program read or wrote to data memory before the present program counter address
appeared. Set up the analyzer to make a trace (with the deMMUer turned on) and
trigger at the logical program counter address (by placing the PC address in the
entry buffer and choosing Trace
→
About (), or using the command trace about
address <pc address>). Selecting a center trigger lets you see activity preceding
and following the trigger point. In order to capture every transaction on the
emulation bus, qualify all states for capture (don’t use the trace only option).
If the access occurs again just before the program counter address you used as your
trigger specification, you should be able to read back in the trace list and find one
or more addresses that could be causing the problem. Then you can try those
suspected addresses in commands (choose Display
→
MMU Translations..., click
on MMU Tables in the dialog box, and enter the suspect addresses, or on the
command line, display mmu_translations tables <suspect_address>) to see how
each of them is mapped through the MMU tables. This should identify the error in
the MMU mapping tables.
If you find a particular address that is mapped to guarded memory, and if the
problem seems to be in Table B (for example), you can look at the details of Table
B for that address by clicking on Table Level B in the Display MMU
Translations... dialog box, or by using a command, such as
display mmu_translations tables <address> level B.
Failure due to system halt
If the emulator or target system or both simply stop operating, set up the analyzer to
trace with a trigger-never specification (Trace
→
Until Stop or trace on_halt) so
that the trace will run continuously until the system stops again. After the system
halt occurs again, read the trace list to find the addresses preceding the system halt.
Check suspected addresses by choosing Display
→
MMU Translations..., clicking
on MMU Tables in the dialog box, and entering the suspect addresses. Or, on the
command line, enter display mmu_translations tables <address> commands to
see how the MMU maps each one to physical memory.
Chapter 10: Using Memory Management
Solving Problems
394