Difference between revisions of "Memory Tecnology Device (MTD)"
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To access and use UBIFS: | To access and use UBIFS: | ||
| − | + | * Add the ubi.mtd=X parameter to the kernel command line, where X is the number of the mtd partition | |
| − | + | * Erase the MTD partition: | |
<pre class="board-terminal"> | <pre class="board-terminal"> | ||
flash_eraseall /dev/mtdX | flash_eraseall /dev/mtdX | ||
</pre> | </pre> | ||
| − | + | * As an alternative to point 1, launch the following command: | |
<pre class="board-terminal"> | <pre class="board-terminal"> | ||
ubiattach /dev/ubi_ctrl -m X | ubiattach /dev/ubi_ctrl -m X | ||
</pre> | </pre> | ||
| − | + | * The device /dev/ubi0 is now available. To create the UBI volume, launch the following command (-N sets the name and -s sets the size of the volume): | |
<pre class="board-terminal"> | <pre class="board-terminal"> | ||
ubimkvol /dev/ubi0 -N rootfs -s 128MiB | ubimkvol /dev/ubi0 -N rootfs -s 128MiB | ||
</pre> | </pre> | ||
| − | + | * The device /dev/ubi0_0 is now available and can be mounted with one of the following comands: | |
<pre class="board-terminal"> | <pre class="board-terminal"> | ||
mount -t ubifs ubi0_0 /mnt/ubifs | mount -t ubifs ubi0_0 /mnt/ubifs | ||
mount -t ubifs ubi0:rootfs /mnt/ubifs | mount -t ubifs ubi0:rootfs /mnt/ubifs | ||
</pre> | </pre> | ||
| − | + | * To mount the UBI file system as root file system, the binding between MTD and UBI must be specified from the kernel command line, adding the following parameters: | |
<pre class="board-terminal"> | <pre class="board-terminal"> | ||
ubi.mtd=6 root=ubi0_0 rootfstype=ubifs rw | ubi.mtd=6 root=ubi0_0 rootfstype=ubifs rw | ||
Revision as of 16:40, 11 May 2012
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Introduction[edit | edit source]
MTD Partitions[edit | edit source]
UBI[edit | edit source]
UBIFS can be considered as the next-generation of the JFFS2 file system. It is a new journaled flash file system which works on top of the UBI (Unsorted Block Images) subsystem, a wear-leveling and volume management system for raw flash devices. UBI volumes are higher level entities than MTD devices, which represents the raw flash devices (/dev/mtdX) and provide the interface to access flash chips. The following figure shows the involved subsystems:
The default MTD partition associated to the NAND flash is mapped as number 4. Let’s assume we run the kernel by using the net_nfs configuration. Since using UBIFS shares some points with using JFFS2, please refer to ... for further details.
To access and use UBIFS:
- Add the ubi.mtd=X parameter to the kernel command line, where X is the number of the mtd partition
- Erase the MTD partition:
flash_eraseall /dev/mtdX
- As an alternative to point 1, launch the following command:
ubiattach /dev/ubi_ctrl -m X
- The device /dev/ubi0 is now available. To create the UBI volume, launch the following command (-N sets the name and -s sets the size of the volume):
ubimkvol /dev/ubi0 -N rootfs -s 128MiB
- The device /dev/ubi0_0 is now available and can be mounted with one of the following comands:
mount -t ubifs ubi0_0 /mnt/ubifs mount -t ubifs ubi0:rootfs /mnt/ubifs
- To mount the UBI file system as root file system, the binding between MTD and UBI must be specified from the kernel command line, adding the following parameters:
ubi.mtd=6 root=ubi0_0 rootfstype=ubifs rw
Please note that
- the file system is formatted automatically the first time it is mounted
- the mount command don't use the /dev/ prefix before ubi0_0 device
