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