diff --git a/doc/tracer.rst b/doc/tracer.rst index e792d44c..9e87950b 100644 --- a/doc/tracer.rst +++ b/doc/tracer.rst @@ -4,4 +4,40 @@ Tracer ====== The module ``ibex_tracer`` can be used to create a log of the executed instructions. -It is used by ``ibex_core_tracing`` which forwards the signals added by :ref:`rvfi` as an input for the tracer. +It is used by ``ibex_core_tracing`` which forwards the `RVFI signals `_ to the tracer (see also :ref:`rvfi`). + +Output file +----------- + +All traced instructions are written to a log file. +By default, the log file is named ``trace_core_.log``, with ```` being the 8 digit hart ID of the core being traced. + +The file name base, defaulting to ``trace_core`` can be set using the ``ibex_tracer_file_base`` plusarg passed to the simulation. +For example, ``+ibex_tracer_file_base=ibex_my_trace`` will produce log files named ``ibex_my_trace_.log``. +The exact syntax of passing plusargs to a simulation depends on the simulator. + +Trace output format +------------------- + +The trace output is in tab-separated columns. + +1. **Time**: The current simulation time. +2. **Cycle**: The number of cycles since the last reset. +3. **PC**: The program counter +4. **Instr**: The executed instruction (base 16). + 32 bit wide instructions (8 hex digits) are uncompressed instructions, 16 bit wide instructions (4 hex digits) are compressed instructions. +5. **Decoded instruction**: The decoded (disassembled) instruction in a format equal to what objdump produces when calling it like ``objdump -Mnumeric -Mno-aliases -D``. + - Unsigned numbers are given in hex (prefixed with ``0x``), signed numbers are given as decimal numbers. + - Numeric register names are used (e.g. ``x1``). + - Symbolic CSR names are used. + - Jump/branch targets are given as absolute address if possible (PC + immediate). +6. **Register and memory contents**: For all accessed registers, the value before and after the instruction execution is given. Writes to registers are indicated as ``registername=value``, reads as ``registername:value``. For memory accesses, the address and the loaded and stored data are given. + +.. code-block:: text + + Time Cycle PC Instr Decoded instruction Register and memory contents + 130 61 00000150 4481 c.li x9,0 x9=0x00000000 + 132 62 00000152 00008437 lui x8,0x8 x8=0x00008000 + 134 63 00000156 fff40413 addi x8,x8,-1 x8:0x00008000 x8=0x00007fff + 136 64 0000015a 8c65 c.and x8,x9 x8:0x00007fff x9:0x00000000 x8=0x00000000 + 142 67 0000015c c622 c.swsp x8,12(x2) x2:0x00002000 x8:0x00000000 PA:0x0000200c store:0x00000000 load:0xffffffff