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esp32: Adds SW flash breakpoints description

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Alexey Gerenkov 2018-07-23 14:18:41 +03:00
parent 0905aa0103
commit 821fe3dc5a
1 changed files with 2 additions and 2 deletions
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4
docs/en/api-guides/jtag-debugging/tips-and-quirks.rst
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@ -9,7 +9,7 @@ This section provides collection of all tips and quirks referred to from various
Breakpoints and watchpoints available
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
The ESP32 supports 2 hardware breakpoints. It also supports two watchpoints, so two variables can be watched for change or read by the GDB command ``watch myVariable``. Note that menuconfig option :envvar:`CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK` uses the 2nd watchpoint and will not provide expected results, if you also try to use it within OpenOCD / GDB. See menuconfig's help for detailed description.
ESP32 debugger supports 2 hardware implemented breakpoints and 64 software ones. Hardware breakpoints are implemented by ESP32 chip's logic and can be set anywhere in the code: either in flash or IRAM program's regions. Additionally there are 2 types of software breakpoints implemented by OpenOCD: flash (up to 32) and IRAM (up to 32) breakpoints. Currently GDB can not set software breakpoints in flash. So until this limitation is removed those breakpoints have to be emulated by OpenOCD as hardware ones (see :ref:`below <jtag-debugging-tip-where-breakpoints>` for details). ESP32 also supports two watchpoints, so two variables can be watched for change or read by the GDB command ``watch myVariable``. Note that menuconfig option :envvar:`CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK` uses the 2nd watchpoint and will not provide expected results, if you also try to use it within OpenOCD / GDB. See menuconfig's help for detailed description.
.. _jtag-debugging-tip-where-breakpoints:
@ -17,7 +17,7 @@ The ESP32 supports 2 hardware breakpoints. It also supports two watchpoints, so
What else should I know about breakpoints?
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Normal GDB breakpoints (``b myFunction``) can only be set in IRAM, because that memory is writable. Setting these types of breakpoints in code in flash will not work. Instead, use a hardware breakpoint (``hb myFunction``).
Emulating part of hardware breakpoints using software flash ones means that the GDB command ``hb myFunction`` which is invoked for function in flash will use pure hardware breakpoint if it is avalable otherwise one of the 32 software flash breakpoints is used. The same rule applies to ``b myFunction``-like commands. In this case GDB will decide what type of breakpoint to set itself. If ``myFunction`` is resided in writable region (IRAM) software IRAM breakpoint will be used otherwise hardware or software flash breakpoint is used as it is done for ``hb`` command.
.. _jtag-debugging-tip-why-next-works-as-step: