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UBI: improve ioctl commentaries
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
This commit is contained in:
Artem Bityutskiy
parent
a27ce8f55d
commit
f7fc6f3f33
@ -40,37 +40,37 @@
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* UBI volume creation
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* ~~~~~~~~~~~~~~~~~~~
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*
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* UBI volumes are created via the %UBI_IOCMKVOL IOCTL command of UBI character
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* UBI volumes are created via the %UBI_IOCMKVOL ioctl command of UBI character
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* device. A &struct ubi_mkvol_req object has to be properly filled and a
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* pointer to it has to be passed to the IOCTL.
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* pointer to it has to be passed to the ioctl.
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*
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* UBI volume deletion
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* ~~~~~~~~~~~~~~~~~~~
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*
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* To delete a volume, the %UBI_IOCRMVOL IOCTL command of the UBI character
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* To delete a volume, the %UBI_IOCRMVOL ioctl command of the UBI character
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* device should be used. A pointer to the 32-bit volume ID hast to be passed
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* to the IOCTL.
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* to the ioctl.
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*
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* UBI volume re-size
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* ~~~~~~~~~~~~~~~~~~
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*
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* To re-size a volume, the %UBI_IOCRSVOL IOCTL command of the UBI character
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* To re-size a volume, the %UBI_IOCRSVOL ioctl command of the UBI character
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* device should be used. A &struct ubi_rsvol_req object has to be properly
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* filled and a pointer to it has to be passed to the IOCTL.
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* filled and a pointer to it has to be passed to the ioctl.
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*
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* UBI volumes re-name
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* ~~~~~~~~~~~~~~~~~~~
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*
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* To re-name several volumes atomically at one go, the %UBI_IOCRNVOL command
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* of the UBI character device should be used. A &struct ubi_rnvol_req object
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* has to be properly filled and a pointer to it has to be passed to the IOCTL.
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* has to be properly filled and a pointer to it has to be passed to the ioctl.
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*
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* UBI volume update
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* ~~~~~~~~~~~~~~~~~
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*
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* Volume update should be done via the %UBI_IOCVOLUP IOCTL command of the
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* Volume update should be done via the %UBI_IOCVOLUP ioctl command of the
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* corresponding UBI volume character device. A pointer to a 64-bit update
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* size should be passed to the IOCTL. After this, UBI expects user to write
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* size should be passed to the ioctl. After this, UBI expects user to write
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* this number of bytes to the volume character device. The update is finished
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* when the claimed number of bytes is passed. So, the volume update sequence
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* is something like:
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@ -80,14 +80,50 @@
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* write(fd, buf, image_size);
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* close(fd);
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*
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* Atomic eraseblock change
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* Logical eraseblock erase
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* ~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* Atomic eraseblock change operation is done via the %UBI_IOCEBCH IOCTL
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* command of the corresponding UBI volume character device. A pointer to
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* &struct ubi_leb_change_req has to be passed to the IOCTL. Then the user is
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* expected to write the requested amount of bytes. This is similar to the
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* "volume update" IOCTL.
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* To erase a logical eraseblock, the %UBI_IOCEBER ioctl command of the
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* corresponding UBI volume character device should be used. This command
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* unmaps the requested logical eraseblock, makes sure the corresponding
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* physical eraseblock is successfully erased, and returns.
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*
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* Atomic logical eraseblock change
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* Atomic logical eraseblock change operation is called using the %UBI_IOCEBCH
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* ioctl command of the corresponding UBI volume character device. A pointer to
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* a &struct ubi_leb_change_req object has to be passed to the ioctl. Then the
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* user is expected to write the requested amount of bytes (similarly to what
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* should be done in case of the "volume update" ioctl).
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*
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* Logical eraseblock map
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* ~~~~~~~~~~~~~~~~~~~~~
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*
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* To map a logical eraseblock to a physical eraseblock, the %UBI_IOCEBMAP
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* ioctl command should be used. A pointer to a &struct ubi_map_req object is
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* expected to be passed. The ioctl maps the requested logical eraseblock to
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* a physical eraseblock and returns. Only non-mapped logical eraseblocks can
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* be mapped. If the logical eraseblock specified in the request is already
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* mapped to a physical eraseblock, the ioctl fails and returns error.
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*
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* Logical eraseblock unmap
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* ~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* To unmap a logical eraseblock to a physical eraseblock, the %UBI_IOCEBUNMAP
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* ioctl command should be used. The ioctl unmaps the logical eraseblocks,
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* schedules corresponding physical eraseblock for erasure, and returns. Unlike
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* the "LEB erase" command, it does not wait for the physical eraseblock being
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* erased. Note, the side effect of this is that if an unclean reboot happens
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* after the unmap ioctl returns, you may find the LEB mapped again to the same
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* physical eraseblock after the UBI is run again.
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*
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* Check if logical eraseblock is mapped
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* To check if a logical eraseblock is mapped to a physical eraseblock, the
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* %UBI_IOCEBISMAP ioctl command should be used. It returns %0 if the LEB is
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* not mapped, and %1 if it is mapped.
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*/
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/*
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@ -101,7 +137,7 @@
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/* Maximum volume name length */
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#define UBI_MAX_VOLUME_NAME 127
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/* IOCTL commands of UBI character devices */
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/* ioctl commands of UBI character devices */
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#define UBI_IOC_MAGIC 'o'
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@ -114,7 +150,7 @@
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/* Re-name volumes */
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#define UBI_IOCRNVOL _IOW(UBI_IOC_MAGIC, 3, struct ubi_rnvol_req)
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/* IOCTL commands of the UBI control character device */
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/* ioctl commands of the UBI control character device */
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#define UBI_CTRL_IOC_MAGIC 'o'
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@ -123,21 +159,21 @@
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/* Detach an MTD device */
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#define UBI_IOCDET _IOW(UBI_CTRL_IOC_MAGIC, 65, int32_t)
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/* IOCTL commands of UBI volume character devices */
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/* ioctl commands of UBI volume character devices */
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#define UBI_VOL_IOC_MAGIC 'O'
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/* Start UBI volume update */
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#define UBI_IOCVOLUP _IOW(UBI_VOL_IOC_MAGIC, 0, int64_t)
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/* An eraseblock erasure command, used for debugging, disabled by default */
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/* LEB erasure command, used for debugging, disabled by default */
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#define UBI_IOCEBER _IOW(UBI_VOL_IOC_MAGIC, 1, int32_t)
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/* An atomic eraseblock change command */
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/* Atomic LEB change command */
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#define UBI_IOCEBCH _IOW(UBI_VOL_IOC_MAGIC, 2, int32_t)
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/* Map an eraseblock, used for debugging, disabled by default */
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/* Map LEB command */
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#define UBI_IOCEBMAP _IOW(UBI_VOL_IOC_MAGIC, 3, struct ubi_map_req)
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/* Unmap an eraseblock, used for debugging, disabled by default */
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/* Unmap LEB command */
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#define UBI_IOCEBUNMAP _IOW(UBI_VOL_IOC_MAGIC, 4, int32_t)
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/* Check if an eraseblock is mapped, used for debugging, disabled by default */
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/* Check if LEB is mapped command */
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#define UBI_IOCEBISMAP _IOR(UBI_VOL_IOC_MAGIC, 5, int32_t)
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/* Maximum MTD device name length supported by UBI */
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@ -311,8 +347,8 @@ struct ubi_rnvol_req {
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} __attribute__ ((packed));
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/**
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* struct ubi_leb_change_req - a data structure used in atomic logical
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* eraseblock change requests.
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* struct ubi_leb_change_req - a data structure used in atomic LEB change
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* requests.
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* @lnum: logical eraseblock number to change
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* @bytes: how many bytes will be written to the logical eraseblock
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* @dtype: data type (%UBI_LONGTERM, %UBI_SHORTTERM, %UBI_UNKNOWN)
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@ -326,7 +362,7 @@ struct ubi_leb_change_req {
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} __attribute__ ((packed));
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/**
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* struct ubi_map_req - a data structure used in map eraseblock requests.
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* struct ubi_map_req - a data structure used in map LEB requests.
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* @lnum: logical eraseblock number to unmap
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* @dtype: data type (%UBI_LONGTERM, %UBI_SHORTTERM, %UBI_UNKNOWN)
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* @padding: reserved for future, not used, has to be zeroed
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