If a fatal error happens inside an ISR, the backtrace may include PC:SP pairs both from the task which was interrupted, and from the ISR.
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The backtrace line contains PC:SP pairs, where PC is the Program Counter and SP is Stack Pointer, for each stack frame of the current task.
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In some cases, such as interrupt watchdog timeout, the panic handler may print additional CPU registers (EPC1-EPC4) and the registers/backtrace of the code running on the other CPU. The register values printed are the register values in the exception frame, i.e., values at the moment when the CPU exception or another fatal error has occurred.Ī Register dump is not printed if the panic handler has been executed as a result of an abort() call. But this may be necessary to debug some complex issues with crashes while flash cache is disabled (for example, when writing to SPI flash) or when flash cache is corrupted when an exception is triggered. If this option is enabled, the panic handler code (including required UART functions) is placed in IRAM, and hence will decrease the usable memory space in SRAM. This adds some minor risk, if the flash cache status is also corrupted during the crash. This means that if ESP-IDF crashes while flash cache is disabled, the panic handler will automatically re-enable flash cache before running GDB Stub or Core Dump. If CONFIG_ESP_PANIC_HANDLER_IRAM is disabled (disabled by default), the panic handler code is placed in flash memory, not IRAM. If the Core Dump feature is enabled, then the system state (task stacks and registers) will be dumped to either Flash or UART, for later analysis. In this case, registers and backtrace are not dumped to the console, and GDBStub / Core Dump functions are not used. If it is, execution will be halted and control will be passed to the debugger. If CONFIG_ESP_DEBUG_OCDAWARE is enabled (which is the default), the panic handler will detect whether a JTAG debugger is connected. The behavior of the panic handler is affected by two other configuration options. This option allows the user to debug a program at run time and set break points, alter the execution, etc. Start GDB server which can communicate with GDB over console UART port. Invoke dynamic GDB Stub ( ESP_SYSTEM_GDBSTUB_RUNTIME) This option will only provide read-only debugging or post-mortem debugging. Invoke GDB Stub ( CONFIG_ESP_SYSTEM_PANIC_GDBSTUB) Silent reboot ( CONFIG_ESP_SYSTEM_PANIC_SILENT_REBOOT)ĭon’t print registers or backtrace, restart the chip immediately. External reset is required to restart the program. Similar to the above option, but halt instead of rebooting.
Print registers and halt ( CONFIG_ESP_SYSTEM_PANIC_PRINT_HALT) This will print register values at the point of the exception, print the backtrace, and restart the chip.
Print registers and reboot ( CONFIG_ESP_SYSTEM_PANIC_PRINT_REBOOT) - default option. Subsequent behavior of the panic handler can be set using CONFIG_ESP_SYSTEM_PANIC configuration choice.
See Guru Meditation Errors for a list of possible error causes. In all cases, the error cause will be printed in parentheses. Exception was unhandled.įor some of the system level checks (interrupt watchdog, cache access error), the message will be similar to Guru Meditation Error: Core 0 panic'ed (Cache disabled but cached memory region accessed). For CPU exceptions, the message will be similar to Guru Meditation Error: Core 0 panic'ed (IllegalInstruction). The panic handler will start by printing the cause of the error to the console. Panic Handler Įvery error cause listed in the Overview will be handled by the panic handler. This guide explains the procedure used in ESP-IDF for handling these errors, and provides suggestions on troubleshooting the errors. Undefined behavior sanitizer (UBSAN) checksįailed assertions, via assert, configASSERT and similar macros. Task watchdog timeout (only fatal if CONFIG_ESP_TASK_WDT_PANIC is set)
In ESP-IDF, these situations include:ĬPU Exceptions: Illegal Instruction, Load/Store Alignment Error, Load/Store Prohibited error, Double Exception. In certain situations, execution of the program can not be continued in a well defined way.
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