[linux-2.6-block.git] / drivers / mtd / ubi / Kconfig

# SPDX-License-Identifier: GPL-2.0-only
menuconfig MTD_UBI
	tristate "Enable UBI - Unsorted block images"
	select CRC32
	help
	  UBI is a software layer above MTD layer which admits use of LVM-like
	  logical volumes on top of MTD devices, hides some complexities of
	  flash chips like wear and bad blocks and provides some other useful
	  capabilities. Please, consult the MTD web site for more details
	  (www.linux-mtd.infradead.org).

if MTD_UBI

config MTD_UBI_WL_THRESHOLD
	int "UBI wear-leveling threshold"
	default 4096
	range 2 65536
	help
	  This parameter defines the maximum difference between the highest
	  erase counter value and the lowest erase counter value of eraseblocks
	  of UBI devices. When this threshold is exceeded, UBI starts performing
	  wear leveling by means of moving data from eraseblock with low erase
	  counter to eraseblocks with high erase counter.

	  The default value should be OK for SLC NAND flashes, NOR flashes and
	  other flashes which have eraseblock life-cycle 100000 or more.
	  However, in case of MLC NAND flashes which typically have eraseblock
	  life-cycle less than 10000, the threshold should be lessened (e.g.,
	  to 128 or 256, although it does not have to be power of 2).

config MTD_UBI_BEB_LIMIT
	int "Maximum expected bad eraseblock count per 1024 eraseblocks"
	default 20
	range 0 768
	help
	  This option specifies the maximum bad physical eraseblocks UBI
	  expects on the MTD device (per 1024 eraseblocks). If the underlying
	  flash does not admit of bad eraseblocks (e.g. NOR flash), this value
	  is ignored.

	  NAND datasheets often specify the minimum and maximum NVM (Number of
	  Valid Blocks) for the flashes' endurance lifetime. The maximum
	  expected bad eraseblocks per 1024 eraseblocks then can be calculated
	  as "1024 * (1 - MinNVB / MaxNVB)", which gives 20 for most NANDs
	  (MaxNVB is basically the total count of eraseblocks on the chip).

	  To put it differently, if this value is 20, UBI will try to reserve
	  about 1.9% of physical eraseblocks for bad blocks handling. And that
	  will be 1.9% of eraseblocks on the entire NAND chip, not just the MTD
	  partition UBI attaches. This means that if you have, say, a NAND
	  flash chip admits maximum 40 bad eraseblocks, and it is split on two
	  MTD partitions of the same size, UBI will reserve 40 eraseblocks when
	  attaching a partition.

	  This option can be overridden by the "mtd=" UBI module parameter or
	  by the "attach" ioctl.

	  Leave the default value if unsure.

config MTD_UBI_FASTMAP
	bool "UBI Fastmap (Experimental feature)"
	default n
	help
	   Important: this feature is experimental so far and the on-flash
	   format for fastmap may change in the next kernel versions

	   Fastmap is a mechanism which allows attaching an UBI device
	   in nearly constant time. Instead of scanning the whole MTD device it
	   only has to locate a checkpoint (called fastmap) on the device.
	   The on-flash fastmap contains all information needed to attach
	   the device. Using fastmap makes only sense on large devices where
	   attaching by scanning takes long. UBI will not automatically install
	   a fastmap on old images, but you can set the UBI module parameter
	   fm_autoconvert to 1 if you want so. Please note that fastmap-enabled
	   images are still usable with UBI implementations without
	   fastmap support. On typical flash devices the whole fastmap fits
	   into one PEB. UBI will reserve PEBs to hold two fastmaps.

	   If in doubt, say "N".

config MTD_UBI_GLUEBI
	tristate "MTD devices emulation driver (gluebi)"
	help
	   This option enables gluebi - an additional driver which emulates MTD
	   devices on top of UBI volumes: for each UBI volumes an MTD device is
	   created, and all I/O to this MTD device is redirected to the UBI
	   volume. This is handy to make MTD-oriented software (like JFFS2)
	   work on top of UBI. Do not enable this unless you use legacy
	   software.

config MTD_UBI_BLOCK
	bool "Read-only block devices on top of UBI volumes"
	default n
	depends on BLOCK
	help
	   This option enables read-only UBI block devices support. UBI block
	   devices will be layered on top of UBI volumes, which means that the
	   UBI driver will transparently handle things like bad eraseblocks and
	   bit-flips. You can put any block-oriented file system on top of UBI
	   volumes in read-only mode (e.g., ext4), but it is probably most
	   practical for read-only file systems, like squashfs.

	   When selected, this feature will be built in the UBI driver.

	   If in doubt, say "N".

config MTD_UBI_FAULT_INJECTION
	bool "Fault injection capability of UBI device"
	default n
	depends on FAULT_INJECTION_DEBUG_FS
	help
	   This option enables fault-injection support for UBI devices for
	   testing purposes.

	   If in doubt, say "N".

config MTD_UBI_NVMEM
	tristate "UBI virtual NVMEM"
	default n
	depends on NVMEM
	help
	   This option enabled an additional driver exposing UBI volumes as NVMEM
	   providers, intended for platforms where UBI is part of the firmware
	   specification and used to store also e.g. MAC addresses or board-
	   specific Wi-Fi calibration data.

	   If in doubt, say "N".

endif # MTD_UBI
Commit	Line	Data
ec8f24b7	1	# SPDX-License-Identifier: GPL-2.0-only
1dd78632 HS	2	menuconfig MTD_UBI
1dd78632 HS	3	tristate "Enable UBI - Unsorted block images"
801c135c AB	4	select CRC32
801c135c AB	5	help
2fae1312	6	UBI is a software layer above MTD layer which admits use of LVM-like
801c135c AB	7	logical volumes on top of MTD devices, hides some complexities of
	8	flash chips like wear and bad blocks and provides some other useful
	9	capabilities. Please, consult the MTD web site for more details
	10	(www.linux-mtd.infradead.org).
	11
1dd78632 HS	12	if MTD_UBI
1dd78632 HS	13
801c135c AB	14	config MTD_UBI_WL_THRESHOLD
	15	int "UBI wear-leveling threshold"
	16	default 4096
	17	range 2 65536
801c135c AB	18	help
	19	This parameter defines the maximum difference between the highest
	20	erase counter value and the lowest erase counter value of eraseblocks
	21	of UBI devices. When this threshold is exceeded, UBI starts performing
	22	wear leveling by means of moving data from eraseblock with low erase
6e0c84e3 AB	23	counter to eraseblocks with high erase counter.
	24
	25	The default value should be OK for SLC NAND flashes, NOR flashes and
	26	other flashes which have eraseblock life-cycle 100000 or more.
	27	However, in case of MLC NAND flashes which typically have eraseblock
3f502622	28	life-cycle less than 10000, the threshold should be lessened (e.g.,
6e0c84e3	29	to 128 or 256, although it does not have to be power of 2).
801c135c	30
8beeb3bb	31	config MTD_UBI_BEB_LIMIT
ba4087e9 RG	32	int "Maximum expected bad eraseblock count per 1024 eraseblocks"
	33	default 20
	34	range 0 768
8beeb3bb SL	35	help
8beeb3bb SL	36	This option specifies the maximum bad physical eraseblocks UBI
ba4087e9 RG	37	expects on the MTD device (per 1024 eraseblocks). If the underlying
	38	flash does not admit of bad eraseblocks (e.g. NOR flash), this value
	39	is ignored.
	40
	41	NAND datasheets often specify the minimum and maximum NVM (Number of
	42	Valid Blocks) for the flashes' endurance lifetime. The maximum
	43	expected bad eraseblocks per 1024 eraseblocks then can be calculated
	44	as "1024 * (1 - MinNVB / MaxNVB)", which gives 20 for most NANDs
	45	(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 reserve
	48	about 1.9% of physical eraseblocks for bad blocks handling. And that
	49	will be 1.9% of eraseblocks on the entire NAND chip, not just the MTD
	50	partition UBI attaches. This means that if you have, say, a NAND
	51	flash chip admits maximum 40 bad eraseblocks, and it is split on two
	52	MTD partitions of the same size, UBI will reserve 40 eraseblocks when
	53	attaching a partition.
	54
db7e21c2 RG	55	This option can be overridden by the "mtd=" UBI module parameter or
db7e21c2 RG	56	by the "attach" ioctl.
edac493d	57
8beeb3bb	58	Leave the default value if unsure.
801c135c	59
76ac66e4 RW	60	config MTD_UBI_FASTMAP
	61	bool "UBI Fastmap (Experimental feature)"
	62	default n
	63	help
	64	Important: this feature is experimental so far and the on-flash
	65	format for fastmap may change in the next kernel versions
	66
	67	Fastmap is a mechanism which allows attaching an UBI device
	68	in nearly constant time. Instead of scanning the whole MTD device it
	69	only has to locate a checkpoint (called fastmap) on the device.
	70	The on-flash fastmap contains all information needed to attach
	71	the device. Using fastmap makes only sense on large devices where
	72	attaching by scanning takes long. UBI will not automatically install
	73	a fastmap on old images, but you can set the UBI module parameter
	74	fm_autoconvert to 1 if you want so. Please note that fastmap-enabled
	75	images are still usable with UBI implementations without
	76	fastmap support. On typical flash devices the whole fastmap fits
	77	into one PEB. UBI will reserve PEBs to hold two fastmaps.
	78
	79	If in doubt, say "N".
	80
801c135c	81	config MTD_UBI_GLUEBI
2ba3d76a	82	tristate "MTD devices emulation driver (gluebi)"
801c135c	83	help
2ba3d76a DP	84	This option enables gluebi - an additional driver which emulates MTD
	85	devices on top of UBI volumes: for each UBI volumes an MTD device is
	86	created, and all I/O to this MTD device is redirected to the UBI
	87	volume. This is handy to make MTD-oriented software (like JFFS2)
	88	work on top of UBI. Do not enable this unless you use legacy
	89	software.
801c135c	90
9d54c8a3 EG	91	config MTD_UBI_BLOCK
	92	bool "Read-only block devices on top of UBI volumes"
	93	default n
22d3ee5c	94	depends on BLOCK
9d54c8a3 EG	95	help
	96	This option enables read-only UBI block devices support. UBI block
	97	devices will be layered on top of UBI volumes, which means that the
	98	UBI driver will transparently handle things like bad eraseblocks and
	99	bit-flips. You can put any block-oriented file system on top of UBI
	100	volumes in read-only mode (e.g., ext4), but it is probably most
	101	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
6931fb44 ZW	107	config MTD_UBI_FAULT_INJECTION
	108	bool "Fault injection capability of UBI device"
	109	default n
	110	depends on FAULT_INJECTION_DEBUG_FS
	111	help
	112	This option enables fault-injection support for UBI devices for
	113	testing purposes.
	114
	115	If in doubt, say "N".
3ce48580 DG	116
	117	config MTD_UBI_NVMEM
	118	tristate "UBI virtual NVMEM"
	119	default n
	120	depends on NVMEM
	121	help
	122	This option enabled an additional driver exposing UBI volumes as NVMEM
	123	providers, intended for platforms where UBI is part of the firmware
	124	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
1dd78632	129	endif # MTD_UBI