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1# SPDX-License-Identifier: GPL-2.0-only2menuconfig MTD_UBI3 tristate "Enable UBI - Unsorted block images"4 select CRC325 help6 UBI is a software layer above MTD layer which admits use of LVM-like7 logical volumes on top of MTD devices, hides some complexities of8 flash chips like wear and bad blocks and provides some other useful9 capabilities. Please, consult the MTD web site for more details10 (www.linux-mtd.infradead.org).11 12if MTD_UBI13 14config MTD_UBI_WL_THRESHOLD15 int "UBI wear-leveling threshold"16 default 409617 range 2 6553618 help19 This parameter defines the maximum difference between the highest20 erase counter value and the lowest erase counter value of eraseblocks21 of UBI devices. When this threshold is exceeded, UBI starts performing22 wear leveling by means of moving data from eraseblock with low erase23 counter to eraseblocks with high erase counter.24 25 The default value should be OK for SLC NAND flashes, NOR flashes and26 other flashes which have eraseblock life-cycle 100000 or more.27 However, in case of MLC NAND flashes which typically have eraseblock28 life-cycle less than 10000, the threshold should be lessened (e.g.,29 to 128 or 256, although it does not have to be power of 2).30 31config MTD_UBI_BEB_LIMIT32 int "Maximum expected bad eraseblock count per 1024 eraseblocks"33 default 2034 range 0 76835 help36 This option specifies the maximum bad physical eraseblocks UBI37 expects on the MTD device (per 1024 eraseblocks). If the underlying38 flash does not admit of bad eraseblocks (e.g. NOR flash), this value39 is ignored.40 41 NAND datasheets often specify the minimum and maximum NVM (Number of42 Valid Blocks) for the flashes' endurance lifetime. The maximum43 expected bad eraseblocks per 1024 eraseblocks then can be calculated44 as "1024 * (1 - MinNVB / MaxNVB)", which gives 20 for most NANDs45 (MaxNVB is basically the total count of eraseblocks on the chip).46 47 To put it differently, if this value is 20, UBI will try to reserve48 about 1.9% of physical eraseblocks for bad blocks handling. And that49 will be 1.9% of eraseblocks on the entire NAND chip, not just the MTD50 partition UBI attaches. This means that if you have, say, a NAND51 flash chip admits maximum 40 bad eraseblocks, and it is split on two52 MTD partitions of the same size, UBI will reserve 40 eraseblocks when53 attaching a partition.54 55 This option can be overridden by the "mtd=" UBI module parameter or56 by the "attach" ioctl.57 58 Leave the default value if unsure.59 60config MTD_UBI_FASTMAP61 bool "UBI Fastmap (Experimental feature)"62 default n63 help64 Important: this feature is experimental so far and the on-flash65 format for fastmap may change in the next kernel versions66 67 Fastmap is a mechanism which allows attaching an UBI device68 in nearly constant time. Instead of scanning the whole MTD device it69 only has to locate a checkpoint (called fastmap) on the device.70 The on-flash fastmap contains all information needed to attach71 the device. Using fastmap makes only sense on large devices where72 attaching by scanning takes long. UBI will not automatically install73 a fastmap on old images, but you can set the UBI module parameter74 fm_autoconvert to 1 if you want so. Please note that fastmap-enabled75 images are still usable with UBI implementations without76 fastmap support. On typical flash devices the whole fastmap fits77 into one PEB. UBI will reserve PEBs to hold two fastmaps.78 79 If in doubt, say "N".80 81config MTD_UBI_GLUEBI82 tristate "MTD devices emulation driver (gluebi)"83 help84 This option enables gluebi - an additional driver which emulates MTD85 devices on top of UBI volumes: for each UBI volumes an MTD device is86 created, and all I/O to this MTD device is redirected to the UBI87 volume. This is handy to make MTD-oriented software (like JFFS2)88 work on top of UBI. Do not enable this unless you use legacy89 software.90 91config MTD_UBI_BLOCK92 bool "Read-only block devices on top of UBI volumes"93 default n94 depends on BLOCK95 help96 This option enables read-only UBI block devices support. UBI block97 devices will be layered on top of UBI volumes, which means that the98 UBI driver will transparently handle things like bad eraseblocks and99 bit-flips. You can put any block-oriented file system on top of UBI100 volumes in read-only mode (e.g., ext4), but it is probably most101 practical for read-only file systems, like squashfs.102 103 When selected, this feature will be built in the UBI driver.104 105 If in doubt, say "N".106 107config MTD_UBI_FAULT_INJECTION108 bool "Fault injection capability of UBI device"109 default n110 depends on FAULT_INJECTION_DEBUG_FS111 help112 This option enables fault-injection support for UBI devices for113 testing purposes.114 115 If in doubt, say "N".116 117config MTD_UBI_NVMEM118 tristate "UBI virtual NVMEM"119 default n120 depends on NVMEM121 help122 This option enabled an additional driver exposing UBI volumes as NVMEM123 providers, intended for platforms where UBI is part of the firmware124 specification and used to store also e.g. MAC addresses or board-125 specific Wi-Fi calibration data.126 127 If in doubt, say "N".128 129endif # MTD_UBI130