| # |
| # 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 |
| ---help--- |
| Enable FAT filesystem support |
| |
| if FS_FAT |
| |
| config FAT_COMPUTE_FSINFO |
| bool "FAT compute free space in FSINFO at mount time" |
| default n |
| ---help--- |
| Enables the computation of free clusters at mount time as suggested by the |
| white paper for FAT. The standard behavior of NuttX is to trust the stored |
| value and only recompute it once required. This works if the file system |
| is never mounted to another OS. SD-cards which are mounted to Windows to |
| modify the content might report wrong space after reinserting it to NuttX. |
| It is recommended to activate this setting if the "SD-Card" is swapped |
| between systems. |
| |
| 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 NOTICE 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 NAME_MAX |
| range 12 255 |
| ---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. |
| |
| This setting may not exceed NAME_MAX. That will be verified at compile |
| time. The minimum values is 12 due to assumptions in internal logic. |
| |
| config FAT_LFN_ALIAS_HASH |
| bool "Use faster method for forming long filename 8.3 alias" |
| depends on FAT_LFN |
| default n |
| ---help--- |
| Long filenames on FAT filesystems have associated 8.3 character alias |
| short filenames. The traditional form of these is FILENA~1.EXT with |
| a running count of the number of similar names. However creating this |
| unique count can take several seconds if there are many similarly named |
| files in the directory. Enabling FAT_LFN_ALIAS_HASH uses an alternative |
| format of FI0123~1.TXT where the four digits are a hash of the original |
| filename. This method is similar to what is used by Windows 2000 and |
| later. |
| |
| config FAT_LFN_UTF8 |
| bool "Allow UTF8 long filenames" |
| depends on FAT_LFN |
| default n |
| ---help--- |
| UTF8 long filenames are accepted and converted to UCS2. |
| |
| config FAT_LFN_ALIAS_TRAILCHARS |
| int "Number of trailing characters to use for 8.3 alias" |
| depends on FAT_LFN |
| default 0 |
| ---help--- |
| Traditional format for long filename 8.3 aliases takes first 6 |
| characters of long filename. If this option is set to N > 0, |
| NuttX will instead take first 6-N and last N characters to form |
| the short name. This is useful for filenames like "datafile12.txt" |
| where the first characters would always remain the same. |
| |
| 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 alignment 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 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 interface 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 |
