diff options
Diffstat (limited to 'kernel/drivers/mtd/ubi/Kconfig')
| -rw-r--r-- | kernel/drivers/mtd/ubi/Kconfig | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/kernel/drivers/mtd/ubi/Kconfig b/kernel/drivers/mtd/ubi/Kconfig new file mode 100644 index 000000000..f0855ce08 --- /dev/null +++ b/kernel/drivers/mtd/ubi/Kconfig @@ -0,0 +1,106 @@ +menuconfig MTD_UBI + tristate "Enable UBI - Unsorted block images" + select CRC32 + help + UBI is a software layer above MTD layer which admits 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". + +endif # MTD_UBI |