Chapter 36. Formatting Support

If the option CYGSEM_FS_FAT_FORMAT is enabled, the filesystem is able to format the chosen volume with a FAT filesystem while mounting it. This is controlled by a number of options passed to the filesystem through the mount function.

format

This option enables formatting. If this is present without an argument, then the volume will only be formatted if the file system cannot be mounted. With an argument of force the volume will be formatted regardless of its current contents. Without this option present, the following options will be ignored.

fat16

This option forces the file system to be formatted using FAT16.

fat32

This option forces the file system to be formatted using FAT32. If neither the fat16 or fat32 options are provided, the formatter will choose the format based on the size of the volume. At present, any volume less than 512MiB in size will be formatted as FAT16, all others will be FAT32.

clsize

This option takes an argument giving the size of each cluster in KiB. It should be a power of 2. If not supplied, the formatter will choose a cluster size based on the size of the volume.

label

This option takes a name which should be up to 11 characters in length. This is used to set the volume label in the boot block and to create a volume label entry in the root directory. If not supplied a default volume label will be set (currently "eCos DISK").

A somewhat contrived example of a mount call with the format option might be as follows:

    err = mount( "/dev/hd0/1", "/disk0",  "fatfs:format=force,fat16,clsize=8,label=My Volume" );

Under normal circumstances, just giving the format option should be sufficient for most purposes:

    err = mount( "/dev/hd0/1", "/disk0",  "fatfs:format" );

This will cause the volume to be formatted according to its size, but only if it is not already mountable.

2017-02-09
Documentation license for this page: eCosPro License