[BUG] ESP32-C3: ELF module execution fails with Instruction access fault

[Abhishekmishra2808]

Description / Steps to reproduce the issue

On ESP32-C3 (esp32c3-devkit:usbconsole), running ELF binaries from examples/elf ROMFS fails with an Instruction access fault. This is reproducible on master,

Steps to reproduce

1. Clone nuttx + nuttx-apps
2. Configure:

   ./tools/configure.sh esp32c3-devkit:usbconsole

Enable: CONFIG_ELF, CONFIG_MODULES, CONFIG_FS_ROMFS, CONFIG_BOARDCTL_ROMDISK, CONFIG_EXAMPLES_ELF, CONFIG_EXAMPLES_ELF_ROMFS, CONFIG_EXECFUNCS_HAVE_SYMTAB, CONFIG_EXECFUNCS_SYSTEM_SYMTAB, CONFIG_NSH_FILE_APPS

3. Build and flash:

• make CROSSDEV=riscv32-esp-elf-
• make CROSSDEV=riscv32-esp-elf- flash ESPTOOL_PORT=/dev/ttyACM0 ESPTOOL_BINDIR=./

4. On NSH: elf

Expected

ELF test binaries from ROMFS should run.

Actual

riscv_exception: EXCEPTION: Instruction access fault
MCAUSE: 00000001, EPC: 3fc8b5d8, MTVAL: 3fc8b5d8
EPC is in DRAM (0x3fc8xxxx), which is not executable on ESP32-C3.

Notes

• libs/libc/elf/elf_load.c uses lib_memalign() (DRAM) when CONFIG_ARCH_USE_TEXT_HEAP is not set.
• Current arch/risc-v/src/esp32c3/ has no up_textheap_memalign().
• Legacy port has arch/risc-v/src/esp32c3-legacy/esp32c3_textheap.c (instruction-bus alias).
• Requesting guidance whether text-heap support should be ported for ELF on current ESP32-C3.

On which OS does this issue occur?

[OS: Linux]

What is the version of your OS?

WSL2 Ubuntu 24.04 (Linux 6.6.87.2-microsoft-standard-WSL2 x86_64)

NuttX Version

master

Issue Architecture

[Arch: risc-v]

Issue Area

[Area: Board support]

Host information

CONFIG_BASE_DEFCONFIG="esp32c3-devkit:usbconsole-dirty"
CONFIG_ARCH_CHIP="esp32c3" CONFIG_ARCH_BOARD="esp32c3-devkit"
CONFIG_ESPRESSIF_USBSERIAL=y
CONFIG_ELF=y
CONFIG_EXAMPLES_ELF=y
CONFIG_EXAMPLES_ELF_ROMFS=y
CONFIG_FS_ROMFS=y
CONFIG_BOARDCTL_ROMDISK=y

Host: Linux WSL2 x86_64 (6.6.87.2-microsoft-standard-WSL2)
Toolchain: riscv32-esp-elf-gcc (crosstool-NG esp-12.2.0_20230208) 12.2.0
Esptool: 5.3.0
HAL: sync/master.c-nuttx-20260428-23-g0eb59f7e02a

Board at test time: ESP32-C3 (QFN32), USB Serial/JTAG, 4MB flash

Verification

• I have verified before submitting the report.

[eren-terzioglu]

Hi,

RTC heap for current Espressif's risc-v implementation is missing and not planned as high priority thing to do. If that feature is needed and planning to implement that I would suggest to take a look at legacy c3 implementation.

Don't want to make a full guide but esp32c3_textheap.c source file is the place that initializes text heap. It is possible to start from here and then it will allocate a space in heap for related operation.

After that it is possible to port rtc heap with checking esp32c3_rtcheap.c source file. It is not a must but that will save some space with using rtc memory as text heap. To initialize rtc memory as text heap that will require some linker script variables. To do that please check _srtcheap and _ertcheap variables on boards/risc-v/esp32c3-legacy/common/scripts folder.

For any other question feel free to ask