Cannot find File after mounting FatFs with VFS in read-only mode.

[andreasp]

Hello, I have a file that I can create and open no problem with a build that uses the

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esp_vfs_fat_spiflash_mount(PERM_STORE_MOUNT_POINT, STORAGE_LABEL,
                                                &mount_config);

function , but if I switch to read only mode using the

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esp_vfs_fat_rawflash_mount(PERM_STORE_MOUNT_POINT, STORAGE_LABEL,
						&mount_config);

function I get the following error: errno(2) = No such file or directory.

This is my config for the spiflash function:

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const esp_vfs_fat_mount_config_t mount_config = {
            .max_files = 3,
            .format_if_mount_failed = true,
            .allocation_unit_size = CONFIG_WL_SECTOR_SIZE
};

This is my config for the rawflash function:

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const esp_vfs_fat_mount_config_t mount_config = {
            .max_files = 3,
            .format_if_mount_failed = false,
};

It mounts just fine but for some reason fopen() cannot find the file anymore. I know for sure that the flashing process or application code is not deleting the file. If I re-flash the spiflash build without the code for creating the file I can still access it. What am I doing wrong?

[ESP_Sprite]

I think the issue is that esp_vfs_fat_spiflash_mount uses a wear leveling layer (needed for writing to flash), while esp_vfs_fat_rawflash_mount uses the raw FAT filesystem without wear leveling (which it can do because it's read-only). In other words: you can't mount a filesystem created for one function using the other function.