[BUG] [ESP32-S3] Enabling CONFIG_SMP prevents mounting the /data directory at startup using MTD/LittleFS

[engdavidiogo]

Description / Steps to reproduce the issue

Description

I noticed a recent issue on ESP32-S3 board configurations related to Wi-Fi (STA/AP): the default esp32s3-devkit:sta_softap configuration does not enable SMP.

When CONFIG_SMP is enabled, board bringup fails during SPI flash storage initialization, and /data (mounted from MTD as non-volatile storage) is not created.

The bringup consistently fails in the flash filesystem setup path.

Base configuration used

./tools/configure.sh esp32s3-devkit:sta_softap

Then SMP was enabled (CONFIG_SMP=y).

Steps to reproduce

1. Configure with:

   ./tools/configure.sh esp32s3-devkit:sta_softap

2. Enable SMP (CONFIG_SMP=y).
3. Build and flash.
4. Boot and run:

   ls /

5. Try manual mount:

   mount -t littlefs -o forceformat /dev/esp32s3flash /data

Expected behavior

• Bringup completes normally.
• /data is created/mounted from SPI flash MTD.
• Manual mount with forceformat succeeds if media is empty/corrupted.

Actual behavior

• Bringup fails in SPI flash filesystem setup.
• /data is not created.
• Manual mount fails with error 28.

Relevant logs

littlefs: lfs_mount failed ret=-14
nx_mount: ERROR: Bind method failed: -14

littlefs: forceformat requested
lfs_dir_commitcrc: commitcrc mismatch at crc-tag block=0x0 off=0x30 ...
lfs_dir_compact: Superblock 0x0 has become unwritable
littlefs: lfs_format failed ret=-28
nx_mount: ERROR: Bind method failed: -28

ERROR: Failed to setup littlefs
ERROR: Failed to initialize SPI Flash: -28

Notes

• Board: ESP32-S3 DevKit
• Wi-Fi mode: STA + AP
• Reproducible when SMP is enabled
• Without SMP, storage bringup path works as expected

On which OS does this issue occur?

[OS: Linux]

What is the version of your OS?

Ubuntu 24

NuttX Version

release 12.12

Issue Architecture

[Arch: xtensa]

Issue Area

[Area: File System]

Host information

No response

Verification

• I have verified before submitting the report.

[Cheng-Logic]

The lfs_format failure with commitcrc mismatch under CONFIG_SMP=y exposes a fatal cross-core cache collision on the ESP32-S3's eXecute-In-Place (XIP) bus. When Core 0 initiates a physical SPI flash Erase/Write, the flash controller temporarily disables the MMU cache; without a symmetric Inter-Processor Call (IPC) barrier, Core 1 continues fetching instructions from the invalidated XIP memory space, causing bus contention that physically corrupts the LittleFS superblock write stream.

// Architected Fix: nuttx/arch/xtensa/src/esp32s3/esp32s3_spiflash.c
// Strict SMP cross-core halting and cache invalidation before MTD flash transactions.

static void esp32s3_spiflash_oplock(void)
{
#ifdef CONFIG_SMP
  // 1. Force hardware-level pause on the sibling CPU via IPC to prevent XIP fetches
  int sibling_cpu = (this_cpu() == 0) ? 1 : 0;
  up_cpu_pause(sibling_cpu);
#endif
  
  // 2. Safely disable cache for the active CPU accessing the SPI Flash Controller
  cache_hal_disable(CACHE_TYPE_ALL);
}

static void esp32s3_spiflash_opunlock(void)
{
  // 1. Restore MMU cache mapping
  cache_hal_enable(CACHE_TYPE_ALL);
  
#ifdef CONFIG_SMP
  // 2. Release the sibling CPU to resume execution
  int sibling_cpu = (this_cpu() == 0) ? 1 : 0;
  up_cpu_resume(sibling_cpu);
#endif
}

[fdcavalcanti]

Hi @engdavidiogo the default file system for this defconfig is ESP32S3_SPIFLASH_SPIFFS.

To use LittleFS you must enable support for it. Did you do it?
Board Selection → Board common logic → Mount SPI Flash MTD on bring-up

Here is the output on master, which works fine with the default SPIFFS:

nsh> echo "Hi there" > /data/hello.txt
nsh> cat /data/hello.txt
Hi there
nsh> 
nsh> mount
  /data type spiffs
  /proc type procfs
nsh> ls /
/:
 data/
 dev/
 proc/
 var/
nsh> ps
  TID   PID  PPID CPU PRI POLICY   TYPE    NPX STATE    EVENT     SIGMASK            STACK COMMAND
    0     0     0   0   0 FIFO     Kthread   - Assigned           0000000000000000 0003040 CPU0 IDLE
    1     0     0   1   0 FIFO     Kthread   - Running            0000000000000000 0003032 CPU1 IDLE
    2     0     0 --- 100 RR       Kthread   - Waiting  Semaphore 0000000000000000 0001968 lpwork 0x3fca7020 0x3fca706c
    3     3     0   0 100 RR       Task      - Running            0000000000000000 0003000 nsh_main
    4     0     0 --- 255 RR       Kthread   - Waiting  Semaphore 0000000000000000 0000688 spiflash_op 0x3fcadb5c
    5     0     0 --- 255 RR       Kthread   - Waiting  Semaphore 0000000000000000 0000688 spiflash_op 0x3fcadb5c
    6     0     0 --- 223 RR       Kthread   - Waiting  Semaphore 0000000000000000 0001984 rt_timer
    7     0     0 --- 253 RR       Kthread   - Waiting  MQ empty  0000000000000000 0006600 wifi
    8     0     0 --- 100 RR       Kthread   - Waiting  Semaphore 0000000000000000 0001968 netdev-wlan0 0x3fcb8028 0
nsh> 

Output using littlefs:

nsh> mount
  /data type littlefs
  /proc type procfs
nsh> echo "Hello littlefs" > /data/hello.txt
nsh> cat /data/hello.txt
Hello littlefs
nsh> 
nsh> ps
  TID   PID  PPID CPU PRI POLICY   TYPE    NPX STATE    EVENT     SIGMASK            STACK COMMAND
    0     0     0   0   0 FIFO     Kthread   - Assigned           0000000000000000 0003040 CPU0 IDLE
    1     0     0   1   0 FIFO     Kthread   - Running            0000000000000000 0003032 CPU1 IDLE
    2     0     0 --- 100 RR       Kthread   - Waiting  Semaphore 0000000000000000 0001968 lpwork 0x3fca7130 0x3fca717c
    3     3     0   0 100 RR       Task      - Running            0000000000000000 0003000 nsh_main
    4     0     0 --- 255 RR       Kthread   - Waiting  Semaphore 0000000000000000 0000688 spiflash_op 0x3fcadd9c
    5     0     0 --- 255 RR       Kthread   - Waiting  Semaphore 0000000000000000 0000688 spiflash_op 0x3fcadd9c
    6     0     0 --- 223 RR       Kthread   - Waiting  Semaphore 0000000000000000 0001984 rt_timer
    7     0     0 --- 253 RR       Kthread   - Waiting  MQ empty  0000000000000000 0006600 wifi
    8     0     0 --- 100 RR       Kthread   - Waiting  Semaphore 0000000000000000 0001968 netdev-wlan0 0x3fcb7c48 0
nsh> 

[engdavidiogo]

Thank you for the feedback, @fdcavalcanti.

Regarding your question about enabling LittleFS support:

Yes, I have enabled LittleFS support and, when CONFIG_SMP is disabled, the behavior is correct —/data is mounted normally during bringup.

However, the issue appears when CONFIG_SMP is enabled in this context.

Enabling dual-core support on the ESP32-S3 (CONFIG_SMP=y) causes the bringup process to fail while attempting to mount the /data directory.

[fdcavalcanti]

If you look at the ps output I added, you will see both cores available, which means SMP is on.

Steps to reproduce:

$ ntxbuild start esp32s3-devkit sta_softap --apps-dir apps
$ ntxbuild kconfig --enable CONFIG_SMP
$ ntxbuild kconfig --enable CONFIG_ESP32S3_SPIFLASH_LITTLEFS
$ ntxbuild build -j10

Tested on NuttX e2f3950d45946eb765dd5fab13a67b7bc70b8a51 and apps e4b84b29d47b98a666df524d6f2d38904c972de5.

Could you erase your entire flash and try again?
Use this to erase:

$ esptool.py erase_flash

Then flash. If you had a different file system before using Little FS, it could cause this issue.