# # For a description of the syntax of this configuration file, # see the file kconfig-language.txt in the NuttX tools repository. # config FS_FAT bool "FAT file system" default n depends on !DISABLE_MOUNTPOINT select FS_READABLE select FS_WRITABLE ---help--- Enable FAT filesystem support if FS_FAT config FAT_LCNAMES bool "FAT upper/lower names" default n ---help--- Enable use of the NT-style upper/lower case 8.3 file name support. config FAT_LFN bool "FAT long file names" default n ---help--- Enable FAT long file names. NOTE: Microsoft claims patents on FAT long file name technology. Please read the disclaimer in the top-level COPYING file and only enable this feature if you understand these issues. config FAT_MAXFNAME int "FAT maximum file name size" depends on FAT_LFN default 32 ---help--- If FAT_LFN is defined, then the default, maximum long file name is 255 bytes. This can eat up a lot of memory (especially stack space). If you are willing to live with some non-standard, short long file names, then define this value to be something more reasonable. A good choice would be the same value as selected for NAME_MAX which will limit the visibility of longer file names anyway. config FS_FATTIME bool "FAT timestamps" default n ---help--- Support FAT date and time. NOTE: There is not much sense in supporting FAT date and time unless you have a hardware RTC or other way to get the time and date. config FAT_FORCE_INDIRECT bool "Force direct transfers" default n ---help--- Normally, the default behavior for the FAT file system is to perform data transfers indirectly though specially allocated sector buffers or, under certain circumstances, directly through user provided buffers . These circumstances are: (1) The transfer is being performed from the beginning of a sector (2) the user-provided buffer will hold the full sector of data. Some hardware, however, may require special DMA-capable memory or specially aligned memory in order to perform the transfers. In this case, there may be no circumstance where the user buffer can be used. Selecting this option will disable all attempts to use the user- provided buffer: All transfers will be force to be performed indirectly through the FAT file systems sector buffers. Note: This will have the negative impact of: (1) An extra data copy to transfer the data between the user buffer and the FAT file systems internal sector buffers, and (2) A loss of performance because I/O will be limited to one sector at a time. This would typically be used with CONFIG_FAT_DMAMEMORY so that special memory allocators are also used and transfers are also performed using only that specially allocated memory. CONFIG_FAT_DMAMEMORY, on the other hand, is often used without CONFIG_FAT_FORCE_INDIRECT when the user memory buffers may come from mixed locations, some of which are DMA-able and some of which are not. But CONFIG_FAT_FORCE_INDIRECT could be used without CONFIG_FAT_DMAMEMORY if there is, for example, only a memory aligment constraints. FORCE_ DMA DIRECT EXAMPLE USAGE INDIRECT MEMORY RETRY Y Y * Use specially allocated memory; Never use caller provided buffer Y N * Not recommended N Y ** Special memory required; user memory has mixed capability; sometimes caller memory is not usable N N Y No special memory but there are alignment requirements; return is caller buffer is not properly aligned N N N User memory can always be used for transfer. * CONFIG_DIRECT_RETRY cannot be selected with CONFIG_FORCE_INDIRECT ** CONFIG_DIRECT_RETRY is automatically selected with CONFIG_DMA_MEMORY config FAT_DMAMEMORY bool "DMA memory allocator" default n select FAT_DIRECT_RETRY if !FAT_FORCE_INDIRECT ---help--- The FAT file system allocates two I/O buffers for data transfer, each are the size of one device sector. One of the buffers is allocated once for each FAT volume that is mounted; the other buffers are allocated each time a FAT file is opened. Some hardware, however, may require special DMA-capable memory in order to perform the transfers. If FAT_DMAMEMORY is defined then the architecture-specific hardware must provide the functions fat_dma_alloc() and fat_dma_free(): fat_dmalloc() will allocate DMA-capable memory of the specified size; fat_dmafree() is the corresponding function that will be called to free the DMA-capable memory. FORCE_ DMA DIRECT EXAMPLE USAGE INDIRECT MEMORY RETRY Y Y * Use specially allocated memory; Never use caller provided buffer Y N * Not recommended N Y ** Special memory required; user memory has mixed capability; sometimes caller memory is not usable N N Y No special memory but there are alignment requirements; return is caller buffer is not properly aligned N N N User memory can always be used for transfer. * CONFIG_DIRECT_RETRY cannot be selected with CONFIG_FORCE_INDIRECT ** CONFIG_DIRECT_RETRY is automatically selected with CONFIG_DMA_MEMORY config FAT_DIRECT_RETRY bool "Direct transfer retry" default y if FAT_DMAMEMORY default n if !FAT_DMAMEMORY depends on !FAT_FORCE_INDIRECT ---help--- The FAT file system contains internal, well aligned sector buffers for indirect data transfer. These transfers are indirect in the sense that that the actual transfer occurs into/out of the sector buffers and an additional copy is necessary to/from the user- provided I/O buffers. But under certain conditions, the FAT file system will use the caller-provided I/O buffers directly to improve efficiency. Those conditions are (1) CONFIG_FAT_FORCE_INDIRECT is not defined, (2) The access is to/from the beginning of a sector, and (3) the user provided buffer is large enough to hold an entire sector. The lower level SDIO driver may have, certain requirements on the memory buffer in order to perform the transfer. Perhaps special DMA memory should be used (with CONFIG_FAT_DMAMEMORY) or perhaps some special memory alignment is required to interace with the hardware. If this option is selected, then the FAT file system will first try the user provided I/O buffer under above conditions. If the transfer fails with -EFAULT. then the FAT file system will try one more time using the internal sector buffers. FORCE_ DMA DIRECT EXAMPLE USAGE INDIRECT MEMORY RETRY Y Y * Use specially allocated memory; Never use caller provided buffer Y N * Not recommended N Y ** Special memory required; user memory has mixed capability; sometimes caller memory is not usable N N Y No special memory but there are alignment requirements; return is caller buffer is not properly aligned N N N User memory can always be used for transfer. * CONFIG_DIRECT_RETRY cannot be selected with CONFIG_FORCE_INDIRECT ** CONFIG_DIRECT_RETRY is automatically selected with CONFIG_DMA_MEMORY endif # FAT