Параметры ядра Linux:Memory Technology Devices
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Параметры ядра Linux | Параметры ядра Linux:Device Drivers
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[править] Memory Technology Device (MTD) support
| Memory Technology Device (MTD) support
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| Memory Technology Devices are flash, RAM and similar chips, often used for solid state file systems on embedded devices. This option will provide the generic support for MTD drivers to register themselves with the kernel and for potential users of MTD devices to enumerate the devices which are present and obtain a handle on them. It will also allow you to select individual drivers for particular hardware and users of MTD devices. If unsure, say N. |
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| Debugging
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| This turns on low-level debugging for the entire MTD sub-system. Normally, you should say N. | |
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| MTD concatenating support
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| Support for concatenating several MTD devices into a single (virtual) one. This allows you to have -for example- a JFFS(2) file system spanning multiple physical flash chips. If unsure, say Y. | |
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| MTD partitioning support
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| If you have a device which needs to divide its flash chip(s) up into multiple 'partitions', each of which appears to the user as a separate MTD device, you require this option to be enabled. If unsure, say 'Y'.
Note, however, that you don't need this option for the DiskOnChip devices. Partitioning on NFTL 'devices' is a different - that's the 'normal' form of partitioning used on a block device. | |
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| Direct char device access to MTD devices
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| This provides a character device for each MTD device present in the system, allowing the user to read and write directly to the memory chips, and also use ioctl() to obtain information about the device, or to erase parts of it. | |
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| Caching block device access to MTD devices
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| Although most flash chips have an erase size too large to be useful as block devices, it is possible to use MTD devices which are based on RAM chips in this manner. This block device is a user of MTD devices performing that function.
At the moment, it is also required for the Journalling Flash File System(s) to obtain a handle on the MTD device when it's mounted (although JFFS and JFFS2 don't actually use any of the functionality of the mtdblock device). Later, it may be extended to perform read/erase/modify/write cycles on flash chips to emulate a smaller block size. Needless to say, this is very unsafe, but could be useful for file systems which are almost never written to. You do not need this option for use with the DiskOnChip devices. For those, enable NFTL support (CONFIG_NFTL) instead. | |
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| Readonly block device access to MTD devices
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| This allows you to mount read-only file systems (such as cramfs) from an MTD device, without the overhead (and danger) of the caching driver.
You do not need this option for use with the DiskOnChip devices. For those, enable NFTL support (CONFIG_NFTL) instead. | ||
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| FTL (Flash Translation Layer) support
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| This provides support for the original Flash Translation Layer which is part of the PCMCIA specification. It uses a kind of pseudo- file system on a flash device to emulate a block device with 512-byte sectors, on top of which you put a 'normal' file system.
You may find that the algorithms used in this code are patented unless you live in the Free World where software patents aren't legal - in the USA you are only permitted to use this on PCMCIA hardware, although under the terms of the GPL you're obviously permitted to copy, modify and distribute the code as you wish. Just not use it. | |
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| NFTL (NAND Flash Translation Layer) support
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| This provides support for the NAND Flash Translation Layer which is used on M-Systems' DiskOnChip devices. It uses a kind of pseudo- file system on a flash device to emulate a block device with 512-byte sectors, on top of which you put a 'normal' file system.
You may find that the algorithms used in this code are patented unless you live in the Free World where software patents aren't legal - in the USA you are only permitted to use this on DiskOnChip hardware, although under the terms of the GPL you're obviously permitted to copy, modify and distribute the code as you wish. Just not use it. | |
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| Write support for NFTL
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| Support for writing to the NAND Flash Translation Layer, as used on the DiskOnChip. | ||
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| INFTL (Inverse NAND Flash Translation Layer) support
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| This provides support for the Inverse NAND Flash Translation Layer which is used on M-Systems' newer DiskOnChip devices. It uses a kind of pseudo-file system on a flash device to emulate a block device with 512-byte sectors, on top of which you put a 'normal' file system.
You may find that the algorithms used in this code are patented unless you live in the Free World where software patents aren't legal - in the USA you are only permitted to use this on DiskOnChip hardware, although under the terms of the GPL you're obviously permitted to copy, modify and distribute the code as you wish. Just not use it. | |
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| Resident Flash Disk (Flash Translation Layer) support
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| This provides support for the flash translation layer known as the Resident Flash Disk (RFD), as used by the Embedded BIOS of General Software. There is a blurb at: | |
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[править] RAM/ROM/Flash chip drivers
| Detect flash chips by Common Flash Interface (CFI) probe
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| The Common Flash Interface specification was developed by Intel, AMD and other flash manufactures that provides a universal method for probing the capabilities of flash devices. If you wish to support any device that is CFI-compliant, you need to enable this option. Visit <http://www.amd.com/products/nvd/overview/cfi.html> for more information on CFI. |
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| Detect non-CFI AMD/JEDEC-compatible flash chips
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| This option enables JEDEC-style probing of flash chips which are not compatible with the Common Flash Interface, but will use the common CFI-targetted flash drivers for any chips which are identified which are in fact compatible in all but the probe method. This actually covers most AMD/Fujitsu-compatible chips, and will shortly cover also non-CFI Intel chips (that code is in MTD CVS and should shortly be sent for inclusion in Linus' tree) |
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| Flash chip driver advanced configuration options
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| If you need to specify a specific endianness for access to flash chips, or if you wish to reduce the size of the kernel by including support for only specific arrangements of flash chips, say 'Y'. This option does not directly affect the code, but will enable other configuration options which allow you to do so.
If unsure, say 'N'. |
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| Support for Intel/Sharp flash chips
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| The Common Flash Interface defines a number of different command sets which a CFI-compliant chip may claim to implement. This code provides support for one of those command sets, used on Intel StrataFlash and other parts. |
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| Support for AMD/Fujitsu flash chips
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| The Common Flash Interface defines a number of different command sets which a CFI-compliant chip may claim to implement. This code provides support for one of those command sets, used on chips including the AMD Am29LV320. |
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| Retry failed commands (erase/program)
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| Some chips, when attached to a shared bus, don't properly filter bus traffic that is destined to other devices. This broken behavior causes erase and program sequences to be aborted when the sequences are mixed with traffic for other devices.
SST49LF040 (and related) chips are know to be broken. | |
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| Support for ST (Advanced Architecture) flash chips
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| The Common Flash Interface defines a number of different command sets which a CFI-compliant chip may claim to implement. This code provides support for one of those command sets. |
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| Support for RAM chips in bus mapping
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| This option enables basic support for RAM chips accessed through a bus mapping driver. |
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| Support for ROM chips in bus mapping
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| This option enables basic support for ROM chips accessed through a bus mapping driver. |
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| Support for absent chips in bus mapping
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| This option enables support for a dummy probing driver used to allocated placeholder MTD devices on systems that have socketed or removable media. Use of this driver as a fallback chip probe preserves the expected registration order of MTD device nodes on the system regardless of media presence. Device nodes created with this driver will return -ENODEV upon access. |
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[править] Mapping drivers for chip access
| Support non-linear mappings of flash chips
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| This causes the chip drivers to allow for complicated paged mappings of flash chips. |
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