xref: /openbmc/u-boot/drivers/mtd/ubi/Kconfig (revision 10e40d54)
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