mmc - a tool for configuring MMC storage devices
mmc [options] [ mmc-block-device]...
mmc-utils is a single-threaded tool that will perform a
specified type of mmc action as specified by the user.
The typical use of mmc-utils is to access the mmc device either for
configuring or reading its configuration registers.
- extcsd
read device
- Read and prints the extended csd register
- extcsd
write offset value
device
- Write value at offset to the device's extcsd
- writeprotect
boot get device
- Print the boot partitions write protect status
- writeprotect
boot set device
[number]
- Set the boot partition write protect status for the device.
If number is passed (0 or 1), only protect that specified eMMC boot
partition, otherwise protect both.
It will be write-protected until the next boot.
- writeprotect
user set type
start-block blocks
device
- Set the write protect configuration for the specified region of the user
area for the device.
start-block specifies the first block of the protected area.
blocks specifies the size of the protected area in blocks.
NOTE! The area must start and end on Write Protect Group boundaries, Use the
"writeprotect user get" command to get the Write Protect Group
size.
type is one of the following:
- none
- Clear temporary write protection.
- temp
- Set temporary write protection.
- pwron
- Set write protection until the next power on.
- writeprotect
user get device
- Print the user area's write protect configuration for the device.
- disable
512B emulation device
- Set the eMMC data sector size to 4KB by disabling emulation on the
device.
- gp create
dry-run length-KiB
partition enh-attr
ext-attr device
- Create general purpose partition for the device.
NOTE! This is a one-time programmable (irreversible) change.
To set enhanced attribute to general partition being created set
enh-attr to 1 else set it to 0.
To set extended attribute to general partition set enh-attr to 1,2
else set it to 0.
dry-run is one of the following:
- -y
- PARTITION_SETTING_COMPLETED in the extcsd will get set and the
partitioning operation will take effect and be finalized.
- -c
- more partitioning settings are still to come - partitioning operation will
not take effect.
- otherwise
- These changes will not take effect neither now nor after a power
cycle.
- enh_area
set dry-run
start-KiB length-KiB
device
- Enable the enhanced user area for the device.
NOTE! This is a one-time programmable (irreversible) change. dry-run
is as above.
- write_reliability
set dry-run partition
device
- Enable write reliability per partition for the device.
NOTE! This is a one-time programmable (irreversible) change. dry-run
is as above.
- status
get device
- Print the response to STATUS_SEND (CMD13).
- bootpart
enable boot-partition
send-ackn device
- Enable the boot partition for the device. Disable the boot partition for
the device if is boot-partition set to 0.
To receive acknowledgment of boot from the card set send-ackn to 1,
else set it to 0.
- bootbus
set boot-mode
reset-boot-bus-conditions
boot-bus-width device
- Set Boot Bus Conditions.
boot-mode is one of the following: single_backward, single_hs, or
dual.
reset-boot-bus-conditions is one of the following: x1 or retain.
boot-bus-width is one of the following: x1, x4, or x8.
- bkops_en
mode device
- Enable the eMMC BKOPS feature on the device. The auto (AUTO_EN) setting is
only supported on eMMC 5.0 or newer.
NOTE! Setting manual (MANUAL_EN) is one-time programmable (irreversible)
change.
mode is one of the following:
- hwreset
enable device
- Permanently enable the eMMC H/W Reset feature on the device.
NOTE! This is a one-time programmable (irreversible) change.
- hwreset
disable device
- Permanently disable the eMMC H/W Reset feature on the device.
NOTE! This is a one-time programmable (irreversible) change.
- sanitize
device [timeout_ms]
- Send Sanitize command to the device. This will delete the unmapped memory
region of the device.
- rpmb
write-key rpmb-device
key-file
- Program authentication key which is 32 bytes length and stored in the
specified file.
Also you can specify '-' instead of key file path to read the key from
stdin.
NOTE! This is a one-time programmable (irreversible) change.
- rpmb
read-counter rpmb-device
- Counter value for the rpmb-device will be read to stdout.
- rpmb
read-block rpmb-device
address blocks-ount
output-le [key-file]
- Blocks of 256 bytes will be read from rpmb-device to output file or
stdout if '-' is specified. If key is specified - read data will be
verified.
- rpmb
write-block rpmb-device
address 256-byte-data-file
key-file
- Block of 256 bytes will be written from data file to rpmb-device.
Also you can specify '-' instead of key file path or data file to read the
data from stdin.
- cache
enable device
- Enable the eMMC cache feature on the device.
NOTE! The cache is an optional feature on devices >= eMMC4.5.
- cache
disable device
- Disable the eMMC cache feature on the device.
NOTE! The cache is an optional feature on devices >= eMMC4.5.
- csd read
device-path
- Print CSD data from device-path. The device path should specify the
csd sysfs file directory.
- cid read
device-path
- Print CID data from device-path. The device path should specify the
cid sysfs file directory.
- scr read
device-path
- Print SCR data from device-path. The device path should specify the
scr sysfs file directory.
- ffu
image-file-name device
[chunk-bytes]
- Run Field Firmware Update with image-file-name on the device.
[chunk-bytes] is optional and defaults to its max - 512k. should be
in decimal bytes and sector aligned.
if [chunk-bytes] is omitted, mmc-utils will try to run ffu using the
largest possible chunks: max(image-file, 512k).
- erase
type start-address
end-address device
- Send Erase CMD38 with specific argument to the device.
NOTE!: This will delete all user data in the specified region of the device.
type is one of the following: legacy, discard, secure-erase,
secure-trim1, secure-trim2, or trim.
- gen_cmd
read device [arg]
- Send GEN_CMD (CMD56) to read vendor-specific format/meaning data from the
device.
NOTE!: [arg] is optional and defaults to 0x1. If [arg] is
specified, then [arg] must be a 32-bit hexadecimal number, prefixed
with 0x/0X. And bit0 in [arg] must be 1. Normally this command is
aimed to extract a device-health info from the device.
- softreset
device
- Issues a CMD0 softreset, e.g. for testing if hardware reset for UHS
works
- boot_operation
boot-data-file device
-
Does the alternative boot operation and writes the specified starting
blocks of boot data into the requested file. Note some limitations:
- 1)
- The boot operation must be configured first, e.g. via bootbus and/or
bootpart commands
- 2)
- The MMC must currently be running at the bus mode that is configured for
the boot operation (HS200 and HS400 not supported at all).
- 3)
- Only up to 512K bytes of boot data will be transferred.
- 4)
- The MMC will perform a soft reset, if your system cannot handle that do
not use the boot operation from mmc-utils.
- --help
| help | -h
- Show the help
- cmd
--help
- Show detailed help for that specific cmd or subset of
commands.
The RPMB partition on the eMMC devices is a special area used for
storing cryptographically safe information signed by a special secret key.
To write and read records from this special area, authentication is needed.
The RPMB area is *only* and *exclusively* accessed using ioctl()s from
user-space.
RPMB commands are send using the mmc multi-ioctl, thus ensures that the atomic
nature of the rpmb access operation.
The rpmb device given as a parameter to the rpmb commands is not a block
device but a char device.
This was done to help the mmc driver to account for some of the rpmb
peculiarities.
RPMB examples
Program rpmb key using the stdin option:
$ echo -n AAAABBBBCCCCDDDDEEEEFFFFGGGGHHHH | mmc rpmb write-key
/dev/mmcblk0rpmb -
Read 2 blocks starting address 2 and output the received content
to stdout. Verify the received frames using the key (not mandatory):
$ echo -n AAAABBBBCCCCDDDDEEEEFFFFGGGGHHHH | mmc rpmb read-block
/dev/mmcblk0rpmb 0x02 2 -
Read 2 blocks without verification starting address 2 and output
the received content to /tmp/block:
$mmc rpmb read-block /dev/mmcblk0rpmb 0x02 2 /tmp/block
Write a string of 'a's to address 2. both the input and key uses
stdin interface:
$ (awk 'BEGIN {while (c++<256) printf "a"}' | echo -n
AAAABBBBCCCCDDDDEEEEFFFFGGGGHHHH) | mmc rpmb write-block /dev/mmcblk0rpmb
0x02 - -
Field Firmware Update (ffu) examples
Do ffu using max-possible chunk size: If the fluf size
< 512k, it will be flushed in a single write sequence.
$ mmc ffu IO4e0aC2056001801M1100042AE1.fluf /dev/mmcblk0
Same as above, this time use a 4k chunks:
$ mmc ffu IO4e0aC2056001801M1100042AE1.fluf /dev/mmcblk0 4096
mmc-utils was written by Chris Ball <cjb@laptop.org>
and <chris@printf.net>.
It is currently maintained by Ulf Hansson <ulf.hansson@linaro.org>.
Report bugs to the mmc mailing list
<linux-mmc@vger.kernel.org>.
For further documentation see README.
A short intro - https://docs.kernel.org/driver-api/mmc/mmc-tools.html
official git tree - https://git.kernel.org/pub/scm/utils/mmc/mmc-utils.git