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92 lines
3.1 KiB
Markdown
92 lines
3.1 KiB
Markdown
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# Debugging events with SystemView and Real-time Terminal (Trezor T only)
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Systemview is an utility to debug interrupts or other events, counters, logs
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which does not require any extra pin (except the SWD pins attached to CPU).
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An example showing two interrupts, and debug log passed via memory instead of UART.
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![SystemView](SystemView_debug_interrupts.png)
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Second example is RTT with color logging (kind of subset what SystemView can do,
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sans the colors).
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![Realtime Terminal](RTTViewer_20201215_165241.png)
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Compared to UART the speed of counters or messages is enormously faster as SystemView
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does trick where it stores all in a small location in RAM (cyclic buffer)
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This requires JLink/JTrace adapter and [SystemView](https://www.segger.com/products/development-tools/systemview/)
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installed. SystemView is available as free/educational or commercial licensed.
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## Building with SystemView enabled
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Clean build in `core`:
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make clean
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### Enable SYSTEM_VIEW
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Change in `SConscript.firmware`: `PYOPT` to `0` (not strictly necessary, but you won't see
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debug messages otherwise, though this enables to use it also on non-debug build).
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Then it's suggested to change `OPTIMIZE` to `-Og` instead of `-Os` which will still
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does optimizations, but only a subset that does hinder debug by reordering
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instructions.
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PYOPT = ARGUMENTS.get('PYOPT', '0')
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COPT=os.getenv('OPTIMIZE', '-Og')
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Then enable the SYSTEM_VIEW feature in `FEATURE_FLAGS`:
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FEATURE_FLAGS = {
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"RDI": True,
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"SECP256K1_ZKP": False,
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"SYSTEM_VIEW": True,
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}
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Then in `core/src/trezor/log.py` change color to False, SystemView does not support
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colorful messages (lines will be garbled), but if you want colors you can also use
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Real-time terminal (RTT, see below)
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set color = False
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Then build with (change PYOPT or BITCOIN_ONLY as needed):
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V=1 VERBOSE=1 PYOPT=0 BITCOIN_ONLY=1 SYSTEM_VIEW=1 make build_embed
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After flashing with:
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make flash_firmware_jlink
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You should be able to conect with SystemView or RTT and collect the data and analyze
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them.
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### Sending data to RTT instead of SystemView
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There are two mutually exclusive macros, first one is turned on by default and sends
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data to SystemView. Changing data sending to RTT is just undefining first and defining
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second (in theory it could be able to send to both destinations, but never tried it.)
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* `SYSTEMVIEW_DEST_SYSTEMVIEW`
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* `SYSTEMVIEW_DEST_RTT`
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Now when you run `JLinkRTTViewerExe` you should see data in the terminal:
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![Realtime Terminal](RTTViewer_20201215_165241.png)
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It is possible to extend this mechanism to include multiple streams/terminals.
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Terminals work like a usual terminal, so you can use it in debugging also for
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user input.
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## Combining SystemView/RTT with other debug tools
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In general you can use SystemView along with GDB/CLion/Ozone or other debugger at the
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same time, it's just advised that you keep all connections at the same frequency,
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otherwise it may lead to unexpected behavior, weird resets, etc.
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So e.g. you can profile the interrupts, DMA in SystemView while also profiling it on
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instruction-level scale in Ozone:
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![Ozone ETM trace with code profile](Ozone_ETM_trace_code_profiling.png)
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