Hi Javier, Littles needs more than 2 blocks. At least 4 are required IIRC, but more to be really functional. When working with flash always remember that a complete page needs to be erased before it can be reused, when there are only 2 blocks everything needs to fit in one block (nothing can be stored in ram because a reboot could destroy it).
Hope this helps, Kind regards, Jehudi On Wed, Oct 22, 2025, 18:12 Javier Alonso <[email protected]> wrote: > Hello devs, > > I'm playing around with some LittleFS configuration on an STM32G0 device. I > have the following snippet: > > ``` > #ifdef CONFIG_MTD_PROGMEM > struct mtd_dev_s * mtd; > /* Initialize on-chip program memory support */ > mtd = stm32_progmem_initialize(); > if (mtd == NULL) > { > syslog(LOG_ERR, "ERROR: stm32_progmem_initialize() failed\n"); > } > else > { > ret = ftl_initialize(0, mtd); > if (ret < 0) > { > syslog(LOG_ERR, "ERROR: ftl_initialize() failed: %d\n", ret); > } > } > #endif /* CONFIG_MTD_PROGMEM */ > #ifdef CONFIG_FS_LITTLEFS > ret = nx_mount("/dev/mtdblock0", "/mnt/progmem", "littlefs", 0, > "autoformat"); > if (ret < 0) > { > syslog(LOG_ERR, "ERROR: Failed to mount littlefs at /mnt/progmem: > %d\n", ret); > } > #endif > ``` > (I'm omitting the internals, but I've implemented the "progmem" layer for > the STM32G0 with the required "up_" functions). > > So far the code runs correctly until the "nx_mount" call is reached. It > fails with "ret = -28", which stands for "ENOSPC". I've been digging around > some forums and it seems the LFS configuration may be wrong. For instance: > > ``` > fs->cfg.context = fs; > fs->cfg.read = littlefs_read_block; > fs->cfg.prog = littlefs_write_block; > fs->cfg.erase = littlefs_erase_block; > fs->cfg.sync = littlefs_sync_block; > fs->cfg.read_size = fs->geo.blocksize * > CONFIG_FS_LITTLEFS_READ_SIZE_FACTOR; > fs->cfg.prog_size = fs->geo.blocksize * > CONFIG_FS_LITTLEFS_PROGRAM_SIZE_FACTOR; > fs->cfg.block_size = fs->geo.erasesize * > CONFIG_FS_LITTLEFS_BLOCK_SIZE_FACTOR; > fs->cfg.block_count = fs->geo.neraseblocks / > CONFIG_FS_LITTLEFS_BLOCK_SIZE_FACTOR; > fs->cfg.block_cycles = CONFIG_FS_LITTLEFS_BLOCK_CYCLE; > fs->cfg.cache_size = fs->geo.blocksize * > CONFIG_FS_LITTLEFS_CACHE_SIZE_FACTOR; > ``` > > The geometry is directly obtained from the underlying FTL MTD device. For > this particular case, I'm reserving 4KB at the end of the flash to be used > as user memory with a fixed page size of 2KB and 2 pages. > > - up_progmem_neraseblocks -> 2 > - up_progmem_isuniform -> true > - up_progmem_pagesize(n) -> 2048 > - up_progmem_erasesize(n) -> 2048 > > I've tried changing the different LFS configurations, so now I have: > > - CONFIG_FS_LITTLEFS_READ_SIZE_FACTOR=1 > - CONFIG_FS_LITTLEFS_PROGRAM_SIZE_FACTOR=1 > - CONFIG_FS_LITTLEFS_BLOCK_SIZE_FACTOR=1 > - CONFIG_FS_LITTLEFS_BLOCK_CYCLE=200 (default) > - CONFIG_FS_LITTLEFS_CACHE_SIZE_FACTOR=1 > - CONFIG_FS_LITTLEFS_LOOKAHEAD_SIZE=0 > - CONFIG_FS_LITTLEFS_ATTR_MAX=1022 (default) > > Is there anything I need to tweak or adjust for LFS to work? So far I've > been unable to make it, it fails on the mount stage. > > Thanks in advance, > > Javier Alonso (he, him, his) > Geotab > > Team Lead - Embedded Systems | GEUR >
