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Based on kernel version 3.13. Page generated on 2014-01-20 21:59 EST.

1	What:		/sys/class/mtd/
2	Date:		April 2009
3	KernelVersion:	2.6.29
4	Contact:	linux-mtd@lists.infradead.org
5	Description:
6			The mtd/ class subdirectory belongs to the MTD subsystem
7			(MTD core).
8	
9	What:		/sys/class/mtd/mtdX/
10	Date:		April 2009
11	KernelVersion:	2.6.29
12	Contact:	linux-mtd@lists.infradead.org
13	Description:
14			The /sys/class/mtd/mtd{0,1,2,3,...} directories correspond
15			to each /dev/mtdX character device.  These may represent
16			physical/simulated flash devices, partitions on a flash
17			device, or concatenated flash devices.
18	
19	What:		/sys/class/mtd/mtdXro/
20	Date:		April 2009
21	KernelVersion:	2.6.29
22	Contact:	linux-mtd@lists.infradead.org
23	Description:
24			These directories provide the corresponding read-only device
25			nodes for /sys/class/mtd/mtdX/ .
26	
27	What:		/sys/class/mtd/mtdX/dev
28	Date:		April 2009
29	KernelVersion:	2.6.29
30	Contact:	linux-mtd@lists.infradead.org
31	Description:
32			Major and minor numbers of the character device corresponding
33			to this MTD device (in <major>:<minor> format).  This is the
34			read-write device so <minor> will be even.
35	
36	What:		/sys/class/mtd/mtdXro/dev
37	Date:		April 2009
38	KernelVersion:	2.6.29
39	Contact:	linux-mtd@lists.infradead.org
40	Description:
41			Major and minor numbers of the character device corresponding
42			to the read-only variant of thie MTD device (in
43			<major>:<minor> format).  In this case <minor> will be odd.
44	
45	What:		/sys/class/mtd/mtdX/erasesize
46	Date:		April 2009
47	KernelVersion:	2.6.29
48	Contact:	linux-mtd@lists.infradead.org
49	Description:
50			"Major" erase size for the device.  If numeraseregions is
51			zero, this is the eraseblock size for the entire device.
52			Otherwise, the MEMGETREGIONCOUNT/MEMGETREGIONINFO ioctls
53			can be used to determine the actual eraseblock layout.
54	
55	What:		/sys/class/mtd/mtdX/flags
56	Date:		April 2009
57	KernelVersion:	2.6.29
58	Contact:	linux-mtd@lists.infradead.org
59	Description:
60			A hexadecimal value representing the device flags, ORed
61			together:
62	
63			0x0400: MTD_WRITEABLE - device is writable
64			0x0800: MTD_BIT_WRITEABLE - single bits can be flipped
65			0x1000: MTD_NO_ERASE - no erase necessary
66			0x2000: MTD_POWERUP_LOCK - always locked after reset
67	
68	What:		/sys/class/mtd/mtdX/name
69	Date:		April 2009
70	KernelVersion:	2.6.29
71	Contact:	linux-mtd@lists.infradead.org
72	Description:
73			A human-readable ASCII name for the device or partition.
74			This will match the name in /proc/mtd .
75	
76	What:		/sys/class/mtd/mtdX/numeraseregions
77	Date:		April 2009
78	KernelVersion:	2.6.29
79	Contact:	linux-mtd@lists.infradead.org
80	Description:
81			For devices that have variable eraseblock sizes, this
82			provides the total number of erase regions.  Otherwise,
83			it will read back as zero.
84	
85	What:		/sys/class/mtd/mtdX/oobsize
86	Date:		April 2009
87	KernelVersion:	2.6.29
88	Contact:	linux-mtd@lists.infradead.org
89	Description:
90			Number of OOB bytes per page.
91	
92	What:		/sys/class/mtd/mtdX/size
93	Date:		April 2009
94	KernelVersion:	2.6.29
95	Contact:	linux-mtd@lists.infradead.org
96	Description:
97			Total size of the device/partition, in bytes.
98	
99	What:		/sys/class/mtd/mtdX/type
100	Date:		April 2009
101	KernelVersion:	2.6.29
102	Contact:	linux-mtd@lists.infradead.org
103	Description:
104			One of the following ASCII strings, representing the device
105			type:
106	
107			absent, ram, rom, nor, nand, mlc-nand, dataflash, ubi, unknown
108	
109	What:		/sys/class/mtd/mtdX/writesize
110	Date:		April 2009
111	KernelVersion:	2.6.29
112	Contact:	linux-mtd@lists.infradead.org
113	Description:
114			Minimal writable flash unit size.  This will always be
115			a positive integer.
116	
117			In the case of NOR flash it is 1 (even though individual
118			bits can be cleared).
119	
120			In the case of NAND flash it is one NAND page (or a
121			half page, or a quarter page).
122	
123			In the case of ECC NOR, it is the ECC block size.
124	
125	What:		/sys/class/mtd/mtdX/ecc_strength
126	Date:		April 2012
127	KernelVersion:	3.4
128	Contact:	linux-mtd@lists.infradead.org
129	Description:
130			Maximum number of bit errors that the device is capable of
131			correcting within each region covering an ECC step (see
132			ecc_step_size).  This will always be a non-negative integer.
133	
134			In the case of devices lacking any ECC capability, it is 0.
135	
136	What:		/sys/class/mtd/mtdX/bitflip_threshold
137	Date:		April 2012
138	KernelVersion:	3.4
139	Contact:	linux-mtd@lists.infradead.org
140	Description:
141			This allows the user to examine and adjust the criteria by which
142			mtd returns -EUCLEAN from mtd_read() and mtd_read_oob().  If the
143			maximum number of bit errors that were corrected on any single
144			region comprising an ecc step (as reported by the driver) equals
145			or exceeds this value, -EUCLEAN is returned.  Otherwise, absent
146			an error, 0 is returned.  Higher layers (e.g., UBI) use this
147			return code as an indication that an erase block may be
148			degrading and should be scrutinized as a candidate for being
149			marked as bad.
150	
151			The initial value may be specified by the flash device driver.
152			If not, then the default value is ecc_strength.
153	
154			The introduction of this feature brings a subtle change to the
155			meaning of the -EUCLEAN return code.  Previously, it was
156			interpreted to mean simply "one or more bit errors were
157			corrected".  Its new interpretation can be phrased as "a
158			dangerously high number of bit errors were corrected on one or
159			more regions comprising an ecc step".  The precise definition of
160			"dangerously high" can be adjusted by the user with
161			bitflip_threshold.  Users are discouraged from doing this,
162			however, unless they know what they are doing and have intimate
163			knowledge of the properties of their device.  Broadly speaking,
164			bitflip_threshold should be low enough to detect genuine erase
165			block degradation, but high enough to avoid the consequences of
166			a persistent return value of -EUCLEAN on devices where sticky
167			bitflips occur.  Note that if bitflip_threshold exceeds
168			ecc_strength, -EUCLEAN is never returned by the read operations.
169			Conversely, if bitflip_threshold is zero, -EUCLEAN is always
170			returned, absent a hard error.
171	
172			This is generally applicable only to NAND flash devices with ECC
173			capability.  It is ignored on devices lacking ECC capability;
174			i.e., devices for which ecc_strength is zero.
175	
176	What:		/sys/class/mtd/mtdX/ecc_step_size
177	Date:		May 2013
178	KernelVersion:	3.10
179	Contact:	linux-mtd@lists.infradead.org
180	Description:
181			The size of a single region covered by ECC, known as the ECC
182			step.  Devices may have several equally sized ECC steps within
183			each writesize region.
184	
185			It will always be a non-negative integer.  In the case of
186			devices lacking any ECC capability, it is 0.
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