I'm going to give it a try, thanks Jehudi!

Although it doesn't fit our needs, we'd need a FS that supports
smaller values. Do you have any suggestions and/or recommendations for
an FS embedded into NuttX that we can use for this purpose? I've been
digging into some NuttX docs about this, but I only found LittleFS to
be the one with examples on how to configure it.

Best regards,

Javier Alonso (he, him, his)
Geotab

Team Lead - Embedded Systems | GEUR

Javier Alonso (he, him, his)
Geotab

Team Lead - Embedded Systems | GEUR


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On Wed, Oct 22, 2025 at 6:24 PM Laczen JMS <[email protected]> wrote:
>
> 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
> >

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