1 menu "UBI support" 2 3 config CONFIG_UBI_SILENCE_MSG 4 bool "UBI silence verbose messages" 5 default ENV_IS_IN_UBI 6 help 7 Make the verbose messages from UBI stop printing. This leaves 8 warnings and errors enabled. 9 10 config MTD_UBI 11 bool "Enable UBI - Unsorted block images" 12 select CRC32 13 select RBTREE 14 select MTD_PARTITIONS 15 help 16 UBI is a software layer above MTD layer which admits of LVM-like 17 logical volumes on top of MTD devices, hides some complexities of 18 flash chips like wear and bad blocks and provides some other useful 19 capabilities. Please, consult the MTD web site for more details 20 (www.linux-mtd.infradead.org). 21 22 if MTD_UBI 23 24 config MTD_UBI_WL_THRESHOLD 25 int "UBI wear-leveling threshold" 26 default 4096 27 range 2 65536 28 help 29 This parameter defines the maximum difference between the highest 30 erase counter value and the lowest erase counter value of eraseblocks 31 of UBI devices. When this threshold is exceeded, UBI starts performing 32 wear leveling by means of moving data from eraseblock with low erase 33 counter to eraseblocks with high erase counter. 34 35 The default value should be OK for SLC NAND flashes, NOR flashes and 36 other flashes which have eraseblock life-cycle 100000 or more. 37 However, in case of MLC NAND flashes which typically have eraseblock 38 life-cycle less than 10000, the threshold should be lessened (e.g., 39 to 128 or 256, although it does not have to be power of 2). 40 41 config MTD_UBI_BEB_LIMIT 42 int "Maximum expected bad eraseblock count per 1024 eraseblocks" 43 default 20 44 range 0 768 45 help 46 This option specifies the maximum bad physical eraseblocks UBI 47 expects on the MTD device (per 1024 eraseblocks). If the underlying 48 flash does not admit of bad eraseblocks (e.g. NOR flash), this value 49 is ignored. 50 51 NAND datasheets often specify the minimum and maximum NVM (Number of 52 Valid Blocks) for the flashes' endurance lifetime. The maximum 53 expected bad eraseblocks per 1024 eraseblocks then can be calculated 54 as "1024 * (1 - MinNVB / MaxNVB)", which gives 20 for most NANDs 55 (MaxNVB is basically the total count of eraseblocks on the chip). 56 57 To put it differently, if this value is 20, UBI will try to reserve 58 about 1.9% of physical eraseblocks for bad blocks handling. And that 59 will be 1.9% of eraseblocks on the entire NAND chip, not just the MTD 60 partition UBI attaches. This means that if you have, say, a NAND 61 flash chip admits maximum 40 bad eraseblocks, and it is split on two 62 MTD partitions of the same size, UBI will reserve 40 eraseblocks when 63 attaching a partition. 64 65 This option can be overridden by the "mtd=" UBI module parameter or 66 by the "attach" ioctl. 67 68 Leave the default value if unsure. 69 70 config MTD_UBI_FASTMAP 71 bool "UBI Fastmap (Experimental feature)" 72 default n 73 help 74 Important: this feature is experimental so far and the on-flash 75 format for fastmap may change in the next kernel versions 76 77 Fastmap is a mechanism which allows attaching an UBI device 78 in nearly constant time. Instead of scanning the whole MTD device it 79 only has to locate a checkpoint (called fastmap) on the device. 80 The on-flash fastmap contains all information needed to attach 81 the device. Using fastmap makes only sense on large devices where 82 attaching by scanning takes long. UBI will not automatically install 83 a fastmap on old images, but you can set the UBI module parameter 84 fm_autoconvert to 1 if you want so. Please note that fastmap-enabled 85 images are still usable with UBI implementations without 86 fastmap support. On typical flash devices the whole fastmap fits 87 into one PEB. UBI will reserve PEBs to hold two fastmaps. 88 89 If in doubt, say "N". 90 91 config MTD_UBI_FASTMAP_AUTOCONVERT 92 int "enable UBI Fastmap autoconvert" 93 depends on MTD_UBI_FASTMAP 94 default 0 95 help 96 Set this parameter to enable fastmap automatically on images 97 without a fastmap. 98 99 config MTD_UBI_FM_DEBUG 100 int "Enable UBI fastmap debug" 101 depends on MTD_UBI_FASTMAP 102 default 0 103 help 104 Enable UBI fastmap debug 105 106 endif # MTD_UBI 107 endmenu # "Enable UBI - Unsorted block images" 108
