IAR ARM BusFault exception when mounting lfs (NO_MALLOC, NO_ASSERT/DEBUG/ERROR/WARN)

[s1syph0s]

Hi,

I want to play around with littlefs for our project for an XMC4500 board. I connected an external NOR FLASH (S25FL) and wrote the driver to interact with the flash. I also created a wrapper function for the lfs to call the read/prog/erase/sync functions, and I allocated a static buffers for the read/prog/lookahead/file.

#define CACHE_SIZE 2048
#define LOOKAHEAD_SIZE 2048

static uint8_t ReadBuf[CACHE_SIZE];
static uint8_t ProgBuf[CACHE_SIZE];
static uint8_t FileBuf[CACHE_SIZE];
static uint8_t LABuf[LOOKAHEAD_SIZE];

const struct lfs_config cfg = {
    .read = my_lfs_read,
    .prog = my_lfs_prog,
    .erase = my_lfs_erase,
    .sync = my_lfs_sync,

    // Device conf
    .read_size = 256,
    .prog_size = 256,
    .block_size = 4096,
    .block_count = 2048,
    .block_cycles = 250,
    .cache_size = CACHE_SIZE,
    .lookahead_size = LOOKAHEAD_SIZE,

    // buffers
    .read_buffer = ReadBuf,
    .prog_buffer = ProgBuf,
    .lookahead_buffer = LABuf,
};

const struct lfs_file_config file_cfg = {
    .buffer = FileBuf,
    .attr_count = 0,
};

lfs_t lfs;
lfs_file_t file;

And during my setup function, lfs_mount is called:

int err = lfs_mount(&lfs, &cfg);
if (err) {
    lfs_format(&lfs, &cfg);
    lfs_mount(&lfs, &cfg);
}

When the lfs_mount function is called, I received a BusFault Exception:

A precise data access error has occurred (CFSR.PRECISERR, BFAR)
At data address 0xf0116801.

An imprecise data access error has occurred (CFSR.IMPRECISERR, BFAR)
At data address 0xf0116801.

While debugging the problem, I found out that the exception happens in my driver, when I send the read opcode through the SPI.

    BYTE cmd = (BYTE) S25FL_READ;
    S25FL_ASSERT(spi_hal_send_data(m_uFlashChannels[idx], &cmd, sizeof(cmd), SPI_ACTION_KEEP_CS_AFTER_TRANSFER));
    
    // m_uFlashChannels is an array of Flash channels; In my current case it has only one element

This only happens if the wrapper my_lfs_read is called from lfs; If I called the function independently without lfs, the exception will not happen and my nor flash is read correctly.

From what I'm reading up until now, this can happen if there's a buffer overflow. Did I configure littlefs incorrectly?

[s1syph0s]

Mounting is now possible. I changed the CACHE_SIZE and LOOKAHEAD_SIZE to 256, and I increased the stack size of my RTOS task to 8192, and now it is possible to read. However, my program hangs again when it tries to call lfs_file_write:

    for (;;) {
        while (spi_device_open(ch_flash, 10) < 0) {
            if (sc_miscErrnoGet() != ETIMEDOUT) {
                kprintf(0, "ERROR %d\n", sc_miscErrnoGet());
                FREEZE;
            }
        }
        // read current count
        uint64_t counter = 0;
        lfs_file_opencfg(&lfs, &file, "counter", LFS_O_RDWR | LFS_O_CREAT, &file_cfg);
        lfs_file_read(&lfs, &file, &counter, sizeof(counter));

        kprintf(0, "Counter: %d\n", counter);

        // update counter
        counter += 1;
        lfs_file_rewind(&lfs, &file);
        lfs_file_write(&lfs, &file, &counter, sizeof(counter));

        lfs_file_close(&lfs, &file);

        if (spi_device_close(ch_flash) < 0) {
            kprintf(0, "ERROR %d\n", sc_miscErrnoGet());
            FREEZE;
        }
        sc_sleep(sc_tickMs2Tick(1000));
    }

The same error like last time happened here. My program crashes in lfs_bd_prog, when it tried to do memcpy lfs.c:242.

[s1syph0s]

I noticed now, that my littlefs is not working properly..

I thought that mounting lfs was now working, but in my code it is actually having an unexpected behavior.

    s25fl_EraseChip(ch_flash); /* Testing to see if the chip will be formatted or not when trying to mount */

    int err = lfs_mount(&lfs, &cfg);
    if (err) {
        lfs_format(&lfs, &cfg);
        lfs_mount(&lfs, &cfg);
    }

I erased the chip before mounting LFS. I expected that lfs_mount call will fail because the chip is erased completely, and should return an error, but I noticed that it doesn't even go inside the if block where the chip will be formatted to LFS format. @geky did I create my configuration correctly?