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