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authorEzequiel Garcia <ezequiel.garcia@free-electrons.com>2014-02-25 13:25:22 -0300
committerArtem Bityutskiy <artem.bityutskiy@linux.intel.com>2014-02-28 16:29:48 +0200
commit9d54c8a33eec78289b1b3f6e10874719c27ce0a7 (patch)
treeba34d64d9dcc1b923f0556da5678ab854b4c529d /include/uapi/mtd
parent5547fec74a566e1f5e00a937b9a367f7c6a94a8b (diff)
UBI: R/O block driver on top of UBI volumes
This commit introduces read-only block device emulation on top of UBI volumes. Given UBI takes care of wear leveling and bad block management it's possible to add a thin layer to enable block device access to UBI volumes. This allows to use a block-oriented filesystem on a flash device. The UBI block devices are meant to be used in conjunction with any regular, block-oriented file system (e.g. ext4), although it's primarily targeted at read-only file systems, such as squashfs. Block devices are created upon user request through new ioctls: UBI_IOCVOLATTBLK to attach and UBI_IOCVOLDETBLK to detach. Also, a new UBI module parameter is added 'ubi.block'. This parameter is needed in order to attach a block device on boot-up time, allowing to mount the rootfs on a ubiblock device. For instance, you could have these kernel parameters: ubi.mtd=5 ubi.block=0,0 root=/dev/ubiblock0_0 Or, if you compile ubi as a module: $ modprobe ubi mtd=/dev/mtd5 block=/dev/ubi0_0 Artem: amend commentaries and massage the patch a little bit. Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Diffstat (limited to 'include/uapi/mtd')
-rw-r--r--include/uapi/mtd/ubi-user.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/include/uapi/mtd/ubi-user.h b/include/uapi/mtd/ubi-user.h
index 723c324590c1..b98585ad3346 100644
--- a/include/uapi/mtd/ubi-user.h
+++ b/include/uapi/mtd/ubi-user.h
@@ -134,6 +134,13 @@
* used. A pointer to a &struct ubi_set_vol_prop_req object is expected to be
* passed. The object describes which property should be set, and to which value
* it should be set.
+ *
+ * Block devices on UBI volumes
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * To attach or detach a block device from an UBI volume the %UBI_IOCVOLATTBLK
+ * and %UBI_IOCVOLDETBLK ioctl commands should be used, respectively.
+ * These commands take no arguments.
*/
/*
@@ -191,6 +198,10 @@
/* Set an UBI volume property */
#define UBI_IOCSETVOLPROP _IOW(UBI_VOL_IOC_MAGIC, 6, \
struct ubi_set_vol_prop_req)
+/* Attach a block device to an UBI volume */
+#define UBI_IOCVOLATTBLK _IO(UBI_VOL_IOC_MAGIC, 7)
+/* Detach a block device from an UBI volume */
+#define UBI_IOCVOLDETBLK _IO(UBI_VOL_IOC_MAGIC, 8)
/* Maximum MTD device name length supported by UBI */
#define MAX_UBI_MTD_NAME_LEN 127

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