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242 lines
7.9 KiB
242 lines
7.9 KiB
What: /sys/class/mtd/ |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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The mtd/ class subdirectory belongs to the MTD subsystem |
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(MTD core). |
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What: /sys/class/mtd/mtdX/ |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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The /sys/class/mtd/mtd{0,1,2,3,...} directories correspond |
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to each /dev/mtdX character device. These may represent |
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physical/simulated flash devices, partitions on a flash |
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device, or concatenated flash devices. |
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What: /sys/class/mtd/mtdXro/ |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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These directories provide the corresponding read-only device |
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nodes for /sys/class/mtd/mtdX/ . |
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What: /sys/class/mtd/mtdX/dev |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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Major and minor numbers of the character device corresponding |
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to this MTD device (in <major>:<minor> format). This is the |
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read-write device so <minor> will be even. |
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What: /sys/class/mtd/mtdXro/dev |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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Major and minor numbers of the character device corresponding |
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to the read-only variant of thie MTD device (in |
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<major>:<minor> format). In this case <minor> will be odd. |
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What: /sys/class/mtd/mtdX/erasesize |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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"Major" erase size for the device. If numeraseregions is |
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zero, this is the eraseblock size for the entire device. |
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Otherwise, the MEMGETREGIONCOUNT/MEMGETREGIONINFO ioctls |
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can be used to determine the actual eraseblock layout. |
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What: /sys/class/mtd/mtdX/flags |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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A hexadecimal value representing the device flags, ORed |
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together: |
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0x0400: MTD_WRITEABLE - device is writable |
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0x0800: MTD_BIT_WRITEABLE - single bits can be flipped |
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0x1000: MTD_NO_ERASE - no erase necessary |
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0x2000: MTD_POWERUP_LOCK - always locked after reset |
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What: /sys/class/mtd/mtdX/name |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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A human-readable ASCII name for the device or partition. |
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This will match the name in /proc/mtd . |
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What: /sys/class/mtd/mtdX/numeraseregions |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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For devices that have variable eraseblock sizes, this |
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provides the total number of erase regions. Otherwise, |
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it will read back as zero. |
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What: /sys/class/mtd/mtdX/oobsize |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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Number of OOB bytes per page. |
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What: /sys/class/mtd/mtdX/size |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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Total size of the device/partition, in bytes. |
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What: /sys/class/mtd/mtdX/type |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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One of the following ASCII strings, representing the device |
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type: |
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absent, ram, rom, nor, nand, mlc-nand, dataflash, ubi, unknown |
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What: /sys/class/mtd/mtdX/writesize |
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Date: April 2009 |
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KernelVersion: 2.6.29 |
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Contact: [email protected] |
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Description: |
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Minimal writable flash unit size. This will always be |
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a positive integer. |
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In the case of NOR flash it is 1 (even though individual |
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bits can be cleared). |
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In the case of NAND flash it is one NAND page (or a |
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half page, or a quarter page). |
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In the case of ECC NOR, it is the ECC block size. |
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What: /sys/class/mtd/mtdX/ecc_strength |
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Date: April 2012 |
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KernelVersion: 3.4 |
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Contact: [email protected] |
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Description: |
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Maximum number of bit errors that the device is capable of |
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correcting within each region covering an ECC step (see |
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ecc_step_size). This will always be a non-negative integer. |
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In the case of devices lacking any ECC capability, it is 0. |
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What: /sys/class/mtd/mtdX/bitflip_threshold |
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Date: April 2012 |
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KernelVersion: 3.4 |
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Contact: [email protected] |
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Description: |
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This allows the user to examine and adjust the criteria by which |
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mtd returns -EUCLEAN from mtd_read() and mtd_read_oob(). If the |
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maximum number of bit errors that were corrected on any single |
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region comprising an ecc step (as reported by the driver) equals |
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or exceeds this value, -EUCLEAN is returned. Otherwise, absent |
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an error, 0 is returned. Higher layers (e.g., UBI) use this |
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return code as an indication that an erase block may be |
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degrading and should be scrutinized as a candidate for being |
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marked as bad. |
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The initial value may be specified by the flash device driver. |
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If not, then the default value is ecc_strength. |
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The introduction of this feature brings a subtle change to the |
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meaning of the -EUCLEAN return code. Previously, it was |
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interpreted to mean simply "one or more bit errors were |
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corrected". Its new interpretation can be phrased as "a |
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dangerously high number of bit errors were corrected on one or |
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more regions comprising an ecc step". The precise definition of |
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"dangerously high" can be adjusted by the user with |
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bitflip_threshold. Users are discouraged from doing this, |
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however, unless they know what they are doing and have intimate |
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knowledge of the properties of their device. Broadly speaking, |
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bitflip_threshold should be low enough to detect genuine erase |
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block degradation, but high enough to avoid the consequences of |
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a persistent return value of -EUCLEAN on devices where sticky |
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bitflips occur. Note that if bitflip_threshold exceeds |
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ecc_strength, -EUCLEAN is never returned by the read operations. |
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Conversely, if bitflip_threshold is zero, -EUCLEAN is always |
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returned, absent a hard error. |
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This is generally applicable only to NAND flash devices with ECC |
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capability. It is ignored on devices lacking ECC capability; |
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i.e., devices for which ecc_strength is zero. |
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What: /sys/class/mtd/mtdX/ecc_step_size |
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Date: May 2013 |
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KernelVersion: 3.10 |
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Contact: [email protected] |
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Description: |
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The size of a single region covered by ECC, known as the ECC |
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step. Devices may have several equally sized ECC steps within |
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each writesize region. |
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It will always be a non-negative integer. In the case of |
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devices lacking any ECC capability, it is 0. |
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What: /sys/class/mtd/mtdX/ecc_failures |
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Date: June 2014 |
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KernelVersion: 3.17 |
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Contact: [email protected] |
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Description: |
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The number of failures reported by this device's ECC. Typically, |
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these failures are associated with failed read operations. |
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It will always be a non-negative integer. In the case of |
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devices lacking any ECC capability, it is 0. |
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What: /sys/class/mtd/mtdX/corrected_bits |
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Date: June 2014 |
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KernelVersion: 3.17 |
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Contact: [email protected] |
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Description: |
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The number of bits that have been corrected by means of the |
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device's ECC. |
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It will always be a non-negative integer. In the case of |
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devices lacking any ECC capability, it is 0. |
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What: /sys/class/mtd/mtdX/bad_blocks |
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Date: June 2014 |
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KernelVersion: 3.17 |
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Contact: [email protected] |
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Description: |
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The number of blocks marked as bad, if any, in this partition. |
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What: /sys/class/mtd/mtdX/bbt_blocks |
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Date: June 2014 |
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KernelVersion: 3.17 |
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Contact: [email protected] |
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Description: |
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The number of blocks that are marked as reserved, if any, in |
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this partition. These are typically used to store the in-flash |
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bad block table (BBT). |
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What: /sys/class/mtd/mtdX/offset |
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Date: March 2015 |
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KernelVersion: 4.1 |
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Contact: [email protected] |
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Description: |
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For a partition, the offset of that partition from the start |
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of the parent (another partition or a flash device) in bytes. |
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This attribute is absent on flash devices, so it can be used |
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to distinguish them from partitions. |
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What: /sys/class/mtd/mtdX/oobavail |
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Date: April 2018 |
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KernelVersion: 4.16 |
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Contact: [email protected] |
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Description: |
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Number of bytes available for a client to place data into |
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the out of band area.
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