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| − | On this page we assume, that you have MTD utils installed as described in [[Linux_Development_for_XScale_modules#MTD_utils|Linux Development for XScale modules]] article.
| + | #REDIRECT [[Linux: JFFS2 images over UBI layer]] |
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| − | == Kernel support ==
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| − | In order to get UBI and UBI GLUE driver working you need to enable them in kernel configuration. In kernel configuration choose '''"Device Drivers -> Memory Technology Device (MTD) support -> UBI - Unsorted block images"''' menu and enable '''"Enable UBI"''' and '''"Emulate MTD devices"''' options.
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| − | <pre>
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| − | ┌─────────────────────────────────── UBI - Unsorted block images ────────────────────────────────────┐
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| − | │ Arrow keys navigate the menu. <Enter> selects submenus --->. Highlighted letters are hotkeys. │
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| − | │ Pressing <Y> includes, <N> excludes, <M> modularizes features. Press <Esc><Esc> to exit, <?> for │
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| − | │ Help, </> for Search. Legend: [*] built-in [ ] excluded <M> module < > module capable │
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| − | │ │
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| − | │ ┌────────────────────────────────────────────────────────────────────────────────────────────────┐ │
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| − | │ │ <*> Enable UBI │ │
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| − | │ │ (4096) UBI wear-leveling threshold (NEW) │ │
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| − | │ │ (1) Percentage of reserved eraseblocks for bad eraseblocks handling (NEW) │ │
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| − | │ │ [*] Emulate MTD devices │ │
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| − | │ │ *** UBI debugging options *** │ │
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| − | │ │ [ ] UBI debugging (NEW) │ │
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| − | │ │ │ │
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| − | │ └────────────────────────────────────────────────────────────────────────────────────────────────┘ │
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| − | ├────────────────────────────────────────────────────────────────────────────────────────────────────┤
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| − | │ <Select> < Exit > < Help > │
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| − | └────────────────────────────────────────────────────────────────────────────────────────────────────┘
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| − | </pre>
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| − | Now you can build the kernel with UBI support including the UBI GLUE driver.
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| − | == User space tools ==
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| − | In this section we will use {{parameter|X}} as the MTD partition number attached to UBI, {{parameter|Y}} as the emulated MTD partition number and we assume that there were no MTD partitions attached to UBI before. <br>
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| − | To prepare the NAND for use with UBI, you should take the following steps:
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| − | * Erase the MTD partition that will be used for UBI volume(s):
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| − | <pre>
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| − | > flash_eraseall /dev/mtdX
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| − | </pre>
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| − | * Attach the MTD partition to UBI:
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| − | <pre>
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| − | > ubiattach /dev/ubi_ctrl -m X -O 2048
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| − | </pre>
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| − | * Create UBI volume:
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| − | <pre>
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| − | > ubimkvol /dev/ubi0 -m -N <ubi volume name>
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| − | </pre>
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| − | * Update the new UBI volume with JFFS2 image:
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| − | <pre>
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| − | > ubiupdatevol /dev/ubi0_0 <path to JFFS2 image>
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| − | </pre>
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| − | If you want to use the new UBI volume as the root filesystem on your device, you should change the {{parameter|root}} parameter of kernel command line to boot from emulated
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| − | MTD partition '''Y''' (which is UBI volume):
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| − | '''root=/dev/mtdblockY''' and add '''ubi.mtd=X,2048''' parameter, so the MTD partition containing the new UBI volume will be attached on kernel boot prior to root filesystem mount.
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| − | == JFFS2 image eraseblock size ==
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| − | UBI layer is using some part of NAND's ''physical'' erase block for it's own needs (e.g. bad blocks handling), therefore it provides a ''logical'' eraseblock for filesystem use. The logical eraseblock size is smaller than the physical, so when you construct the JFFS2 image, as described in section [[Linux_Development_for_XScale_modules#JFFS2_images|JFFS2 images]], you should set the {{parameter|eraseblock}} parameter to UBI's logical eraseblock size. <br> | |
| − | The UBI logical eraseblock size can be obtained by invoking the command:
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| − | <pre>
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| − | > cat /sys/class/ubi/ubiX/eraseblock_size
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| − | </pre>
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| − | Where {{parameter|X}} is the UBI device number.
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| − | == See also ==
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| − | * [[Linux_Development_for_XScale_modules|Linux Development for XScale modules]]
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| − | * [[Linux_MTD_drivers_on_CM-X270|Linux MTD drivers on CM-X270]]
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| − | * [[Getting_started_with_Linux_on_CM-X300|Getting started with Linux on CM-X300]]
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| − | * [http://www.linux-mtd.infradead.org/doc/ubi.html UBI documentation]
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| − | * [http://www.linux-mtd.infradead.org/faq/ubi.html UBI FAQ and HOWTO]
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