1menuconfig MTD_UBI 2 tristate "Enable UBI - Unsorted block images" 3 select CRC32 4 help 5 UBI is a software layer above MTD layer which admits of LVM-like 6 logical volumes on top of MTD devices, hides some complexities of 7 flash chips like wear and bad blocks and provides some other useful 8 capabilities. Please, consult the MTD web site for more details 9 (www.linux-mtd.infradead.org). 10 11if MTD_UBI 12 13config MTD_UBI_WL_THRESHOLD 14 int "UBI wear-leveling threshold" 15 default 4096 16 range 2 65536 17 help 18 This parameter defines the maximum difference between the highest 19 erase counter value and the lowest erase counter value of eraseblocks 20 of UBI devices. When this threshold is exceeded, UBI starts performing 21 wear leveling by means of moving data from eraseblock with low erase 22 counter to eraseblocks with high erase counter. 23 24 The default value should be OK for SLC NAND flashes, NOR flashes and 25 other flashes which have eraseblock life-cycle 100000 or more. 26 However, in case of MLC NAND flashes which typically have eraseblock 27 life-cycle less than 10000, the threshold should be lessened (e.g., 28 to 128 or 256, although it does not have to be power of 2). 29 30config MTD_UBI_BEB_RESERVE 31 int "Percentage of reserved eraseblocks for bad eraseblocks handling" 32 default 2 33 range 0 25 34 help 35 If the MTD device admits of bad eraseblocks (e.g. NAND flash), UBI 36 reserves some amount of physical eraseblocks to handle new bad 37 eraseblocks. When a physical eraseblock becomes bad, UBI uses these 38 reserved physical eraseblocks to relocate the bad one. This 39 configuration option specifies how many physical eraseblocks will be 40 reserved for bad eraseblock handling (percents of total number of 41 good physical eraseblocks on this MTD partition). If the underlying 42 flash does not admit of bad eraseblocks (e.g. NOR flash), this value 43 is ignored and nothing is reserved. Leave the default value if 44 unsure. 45 46config MTD_UBI_BEB_LIMIT 47 int "Percentage of maximum expected bad eraseblocks" 48 default 2 49 range 0 25 50 help 51 This option specifies the maximum bad physical eraseblocks UBI 52 expects on the UBI device (percents of total number of physical 53 eraseblocks on this MTD partition). If the underlying flash does not 54 admit of bad eraseblocks (e.g. NOR flash), this value is ignored. 55 Leave the default value if unsure. 56 57config MTD_UBI_GLUEBI 58 tristate "MTD devices emulation driver (gluebi)" 59 help 60 This option enables gluebi - an additional driver which emulates MTD 61 devices on top of UBI volumes: for each UBI volumes an MTD device is 62 created, and all I/O to this MTD device is redirected to the UBI 63 volume. This is handy to make MTD-oriented software (like JFFS2) 64 work on top of UBI. Do not enable this unless you use legacy 65 software. 66 67endif # MTD_UBI 68