From d5e76347f8e09b589d7a4635bff122665ed52523 Mon Sep 17 00:00:00 2001 From: Judith Mendez Date: Fri, 13 Dec 2024 15:23:49 -0600 Subject: [PATCH] refactor: Refactor the MMC documentation in MMC-SD Fix the MMC documentation in MMC-SD. The file has been patched up in a way that is uneccessarily difficult to browse. Fix up the documentation sections and whitespace. While we are here add additional necessary sections for MMC. Signed-off-by: Judith Mendez --- .../Kernel/Kernel_Drivers/Storage/MMC-SD.rst | 476 +++++++++++------- 1 file changed, 288 insertions(+), 188 deletions(-) diff --git a/source/linux/Foundational_Components/Kernel/Kernel_Drivers/Storage/MMC-SD.rst b/source/linux/Foundational_Components/Kernel/Kernel_Drivers/Storage/MMC-SD.rst index ef2a40aad..035d9a316 100644 --- a/source/linux/Foundational_Components/Kernel/Kernel_Drivers/Storage/MMC-SD.rst +++ b/source/linux/Foundational_Components/Kernel/Kernel_Drivers/Storage/MMC-SD.rst @@ -1,10 +1,10 @@ .. http://processors.wiki.ti.com/index.php/Linux_Core_MMC/SD_User%27s_Guide MMC/SD ---------------------------------- +###### Introduction -^^^^^^^^^^^^ +************ The multimedia card high-speed/SDIO (MMC/SDIO) host controller provides an interface between a local host (LH) such as a microprocessor unit @@ -16,7 +16,6 @@ intervention. Main features of the MMC/SDIO host controllers: - - Full compliance with MMC/SD command/response sets as defined in the Specification. @@ -32,23 +31,18 @@ intervention. - Maximum operating frequency of 48MHz - MMC/SD card hot insertion and removal -.. Image:: /images/Mmcsd_Driver.png - -MMC/SD Driver Architecture +The following image shows the MMC/SD Driver Architecture: -| +.. Image:: /images/Mmcsd_Driver.png References -^^^^^^^^^^ - -#. JEDEC eMMC Homepage - [http://www.jedec.org/category/technology-focus-area/flash-memory-ssds-ufs-emmc] -#. SD ORG Homepage [http://www.sdcard.org] +********** -| +#. `JEDEC eMMC homepage `__ +#. `SD organization homepage `__ Acronyms & Definitions -^^^^^^^^^^^^^^^^^^^^^^ +********************** +-----------+--------------------+ | Acronym | Definition | @@ -64,12 +58,8 @@ Acronyms & Definitions | SDIO | SD Input/Output | +-----------+--------------------+ -Table: **MMC/SD: Acronyms** - -| - Features -^^^^^^^^ +******** .. ifconfig:: CONFIG_part_family in ('General_family', 'AM335X_family', 'AM437X_family') @@ -79,7 +69,7 @@ Features - SD cards including SD High Speed and SDHC cards - Uses block bounce buffer to aggregate scattered blocks -.. ifconfig:: CONFIG_part_family in ('J7_family') +.. ifconfig:: CONFIG_part_family in ('J7_family', 'AM62PX_family') The SD/MMC driver supports the following features: @@ -88,36 +78,45 @@ Features - Support for both built-in and module mode - ext2/ext3/ext4 file system support -Supported High Speed Modes -^^^^^^^^^^^^^^^^^^^^^^^^^^ - -.. ifconfig:: CONFIG_part_family in ('General_family') - - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - | Platform | SDR104 | DDR50 | SDR50 | SDR25 | SDR12 | - +====================+===================+===================+===================+===================+===================+ - | DRA74-EVM | Y | Y | Y | Y | Y | - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - | DRA72-EVM | Y | Y | Y | Y | Y | - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - | DRA71-EVM | Y | Y | Y | Y | Y | - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - | DRA72-EVM-REVC | Y | Y | Y | Y | Y | - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - | AM57XX-EVM | N | N | N | N | N | - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - | AM57XX-EVM-REVA3 | N | N | N | N | N | - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - | AM572X-IDK | N | N | N | N | N | - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - | AM571X-IDK | N | N | N | N | N | - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - | AM654-SR2-EVM | Y | Y | Y | Y | Y | - +--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+ - - Table: **MMC1/SD** - - **Note**: In AM654-SR1-EVM none of the UHS modes are supported. +.. ifconfig:: CONFIG_part_family in ('AM62X_family', 'AM62AX_family', 'AM64X_family') + + The SD/MMC driver supports the following features: + + - Support ADMA for DMA transfers + - HS200 speed mode + - Support for both built-in and module mode + - ext2/ext3/ext4 file system support + +SD: Supported High Speed Modes +****************************** + +.. ifconfig:: CONFIG_part_family in ('General_family', 'AM57X_family', 'AM65X_family') + + +--------------------+--------+-------+-------+-------+-------+ + | Platform | SDR104 | DDR50 | SDR50 | SDR25 | SDR12 | + +====================+========+=======+=======+=======+=======+ + | DRA74-EVM | Y | Y | Y | Y | Y | + +--------------------+--------+-------+-------+-------+-------+ + | DRA72-EVM | Y | Y | Y | Y | Y | + +--------------------+--------+-------+-------+-------+-------+ + | DRA71-EVM | Y | Y | Y | Y | Y | + +--------------------+--------+-------+-------+-------+-------+ + | DRA72-EVM-REVC | Y | Y | Y | Y | Y | + +--------------------+--------+-------+-------+-------+-------+ + | AM57XX-EVM | N | N | N | N | N | + +--------------------+--------+-------+-------+-------+-------+ + | AM57XX-EVM-REVA3 | N | N | N | N | N | + +--------------------+--------+-------+-------+-------+-------+ + | AM572X-IDK | N | N | N | N | N | + +--------------------+--------+-------+-------+-------+-------+ + | AM571X-IDK | N | N | N | N | N | + +--------------------+--------+-------+-------+-------+-------+ + | AM654-SR2-EVM | Y | Y | Y | Y | Y | + +--------------------+--------+-------+-------+-------+-------+ + + .. note:: + + In AM654-SR1-EVM none of the UHS modes are supported. **Important Info**: Certain UHS cards do not enumerate. The list of functional UHS cards is given in the following tables @@ -179,8 +178,6 @@ Supported High Speed Modes | AM654-SR2-EVM | Y | Y | +--------------------+-------+---------+ - Table: **MMC2/EMMC** - .. ifconfig:: CONFIG_part_family in ('J7_family') * SD @@ -211,8 +208,32 @@ Supported High Speed Modes J721e-sk and AM68-sk does not support eMMC. +.. ifconfig:: CONFIG_part_variant in ('AM62X', 'AM62AX', 'AM64X', 'AM62PX' ) + + * SD + + .. csv-table:: + :header: "Platform", "SDR104", "DDR50", "SDR50", "SDR25", "SDR12" + :widths: auto + + AM62*, Y, Y, Y, Y, Y + AM62ax, Y, Y, Y, Y, Y + am64x, Y, Y, Y, Y, Y + am62px, Y, Y, Y, Y, Y + + * eMMC + + .. csv-table:: + :header: "Platform", "DDR52", "HS200", "HS400" + :widths: auto + + AM62*, Y, Y, N + AM62ax, Y, Y, N + am64x, Y, Y, N + am62px, Y, Y, Y + Driver Configuration -^^^^^^^^^^^^^^^^^^^^ +******************** .. ifconfig:: CONFIG_part_family in ('General_family', 'AM335X_family', 'AM437X_family') @@ -221,9 +242,9 @@ Driver Configuration The selection of MMC/SD/SDIO driver can be modified using the linux kernel configuration tool. Launch it by the following command: - :: + .. code-block:: console - $ make menuconfig ARCH=arm + $ make menuconfig ARCH=arm .. rubric:: **Building into Kernel** :name: building-into-kernel-mmcsd @@ -232,8 +253,8 @@ Driver Configuration * CONFIG_MMC * CONFIG_MMC_BLOCK * CONFIG_MMC_SDHCI - * CONFIG_MMC_SDHCI_OMAP (for DRA7XX and AM57XX devices) - * CONFIG_MMC_OMAP (for AM335X and AM437X devices) + * CONFIG_MMC_SDHCI_OMAP (for DRA7XX and AM57XX devices) + * CONFIG_MMC_OMAP (for AM335X and AM437X devices) .. rubric:: **Building as Loadable Kernel Module** @@ -241,23 +262,23 @@ Driver Configuration to build them as a module. Use the following command to install all modules tp your filesystem. - :: + .. code-block:: console - # sudo -E make modules_install ARCH=arm INSTALL_MOD_PATH=path/to/filesystem + $ sudo -E make modules_install ARCH=arm INSTALL_MOD_PATH=path/to/filesystem Boot the kernel upto kernel prompt and use modprobe to insert the driver module and all its dependencies. - :: + .. code-block:: console - # modprobe sdhci-omap (for DRA7XX and AM57XX devices) - # modprobe omap_hsmmc (for AM335X and AM437X devices) + $ modprobe sdhci-omap # for DRA7XX and AM57XX devices + $ modprobe omap_hsmmc # for AM335X and AM437X devices - If 'udev' is running and the SD card is already inserted, the devices - nodes will be created and filesystem will be automatically mounted if - exists on the card. + If **udev** is running and the SD card is already inserted, the required + modules will be loaded and any valid filesystem will be automatically mounted + if they exist on the card. -.. ifconfig:: CONFIG_part_family in ('J7_family') +.. ifconfig:: CONFIG_part_family in ('J7_family', 'AM62X_family', 'AM64X_family', 'AM62AX_family', 'AM62PX_family') The default kernel configuration enables support for MMC/SD driver as built-in to kernel. TI SDHCI driver is used. Following options need to be @@ -266,7 +287,7 @@ Driver Configuration - Enable SDHCI support (CONFIG_MMC_SDHCI) - .. code-block:: text + .. code-block:: Kconfig Device Drivers --> MMC/SD/SDIO card support --> @@ -274,7 +295,7 @@ Driver Configuration - Enable SDHCI platform helper (CONFIG_MMC_SDHCI_PLTFM) - .. code-block:: text + .. code-block:: Kconfig Device Drivers --> MMC/SD/SDIO card support --> @@ -283,7 +304,7 @@ Driver Configuration - Enable SDHCI controller for TI device (CONFIG_MMC_SDHCI_AM654) - .. code-block:: text + .. code-block:: Kconfig Device Drivers --> MMC/SD/SDIO card support --> @@ -294,18 +315,23 @@ Driver Configuration .. rubric:: **Enabling eMMC Card Background operations support** :name: enabling-emmc-card-background-operations-support - | eMMC cards need to occasionally spend some time cleaning up garbage - and perform cache/buffer related operations which are strictly on the - card side and do not involve the host. These operations are at various - levels based on the importance/severity of the operation 1- Normal, 2- - Important and 3 - Critical. If an operation is delayed for long it - becomes critical and the regular read/write from host can be delayed - or take more time than expected. - | To avoid such issues the MMC HW and core driver provide a framework - which can check for pending background operations and give the card - some time to clear up the same. - | This feature is already part of the framework and to start using it - the User needs to enable EXT\_CSD : BKOPS\_EN [163] BIT 0. + eMMC cards need to occasionally spend some time cleaning up garbage and + perform cache/buffer related operations. These are strictly on the card + side and do not involve the host. They occur at one of the three + levels based on the importance/severity of the operation: + + 1. Normal + 2. Important + 3. Critical + + If an operation is delayed for too long, it becomes critical, taking + priority over the regular read/write from host. This can cause host + operations to be delayed or take more time than expected. To avoid such + issues the MMC HW and core driver provide a framework which can check + for pending background operations and give the card some time to service + them before they become critical. This feature is already part of the + framework and to start using it the User needs to enable: + EXT\_CSD : BKOPS\_EN [163] BIT 0. **This can be done using the "mmc-utils" tool from user space or using the "mmc" command in U-boot.** @@ -313,141 +339,215 @@ Driver Configuration Command to enable bkops from userspace using mmc-utils, assuming eMMC instance to be mmcblk0 - :: + .. code-block:: console - root@dra7xx-evm:mmc bkops enable /dev/mmcblk0 + root@:mmc bkops enable /dev/mmcblk0 You can find the instance of eMMC by reading the ios timing spec form - debugfs + debugfs: - :: + .. code-block:: console - root@dra7xx-evm:~# cat /sys/kernel/debug/mmc0/ios - ---- - timing spec: 9 (mmc HS200) - --- + root@:~# cat /sys/kernel/debug/mmc0/ios + ---- + timing spec: 9 (mmc HS200) + --- - or by looking for boot partitions, eMMC has two bootpartitions + or by looking for boot partitions, eMMC has two boot partitions mmcblkboot0 and mmcblkboot1 - :: + .. code-block:: console + + root@:/# ls /dev/mmcblk*boot* + /dev/mmcblk0boot0 /dev/mmcblk0boot1 + +| + +.. ifconfig:: CONFIG_part_family not in ('General_family', 'AM57X_family', 'AM335X_family', 'AM437X_family') - root@dra7xx-evm:/# ls /dev/mmcblk*boot* - /dev/mmcblk0boot0 /dev/mmcblk0boot1 + Steps for working around SD card issues in Linux + ************************************************ -Steps for working around SD card issues -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + In some cases, failures can be seen while using some SD cards: -In some cases failure can be seen while using some SD cards, + - Kernel fails to enumerate SD, thus failing to mount the root file system. This is + the case when kernel hangs during boot with a message similar to the following: -#. Kernel fails to enumerate SD, thus failing to mount the root file - system. This is the case when kernel hangs during boot with a message - similar to the following, + .. code-block:: dmesg + + [ 2.563279] Waiting for root device PARTUUID=835b171b-02... - :: + - A lot of SDHCI register dumps logs getting printed continuously: - [ 2.563279] Waiting for root device PARTUUID=835b171b-02... + .. code-block:: dmesg + [ 10.811723] mmc1: Got data interrupt 0x00000002 even though no data operation was in progress. + [ 10.820321] mmc1: sdhci: ============ SDHCI REGISTER DUMP =========== + [ 10.826745] mmc1: sdhci: Sys addr: 0x00000080 | Version: 0x00001004 + [ 10.833169] mmc1: sdhci: Blk size: 0x00007200 | Blk cnt: 0x00000080 + [ 10.839593] mmc1: sdhci: Argument: 0x00000000 | Trn mode: 0x00000033 + [ 10.846016] mmc1: sdhci: Present: 0x01f70000 | Host ctl: 0x0000001f + [ 10.852440] mmc1: sdhci: Power: 0x0000000f | Blk gap: 0x00000080 + [ 10.858864] mmc1: sdhci: Wake-up: 0x00000000 | Clock: 0x00000007 + [ 10.865287] mmc1: sdhci: Timeout: 0x00000000 | Int stat: 0x00000000 + [ 10.871711] mmc1: sdhci: Int enab: 0x03ff008b | Sig enab: 0x03ff008b + [ 10.878134] mmc1: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000000 + [ 10.884557] mmc1: sdhci: Caps: 0x3de8c801 | Caps_1: 0x18002407 + [ 10.890981] mmc1: sdhci: Cmd: 0x00000c1a | Max curr: 0x00000000 + [ 10.897404] mmc1: sdhci: Resp[0]: 0x00000b00 | Resp[1]: 0x0075cf7f + [ 10.903828] mmc1: sdhci: Resp[2]: 0x32db7900 | Resp[3]: 0x00000900 + [ 10.910251] mmc1: sdhci: Host ctl2: 0x0000000b + [ 10.914682] mmc1: sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x00000000a2e90200 -#. A lot of SDHCI register dumps logs getting printed continuously, - - :: + Given below are the list of various workarounds that can be done in the device tree + node to get SD card working. The workarounds are ordered from least to most performance + impacting. - [ 10.811723] mmc1: Got data interrupt 0x00000002 even though no data operation was in progress. - [ 10.820321] mmc1: sdhci: ============ SDHCI REGISTER DUMP =========== - [ 10.826745] mmc1: sdhci: Sys addr: 0x00000080 | Version: 0x00001004 - [ 10.833169] mmc1: sdhci: Blk size: 0x00007200 | Blk cnt: 0x00000080 - [ 10.839593] mmc1: sdhci: Argument: 0x00000000 | Trn mode: 0x00000033 - [ 10.846016] mmc1: sdhci: Present: 0x01f70000 | Host ctl: 0x0000001f - [ 10.852440] mmc1: sdhci: Power: 0x0000000f | Blk gap: 0x00000080 - [ 10.858864] mmc1: sdhci: Wake-up: 0x00000000 | Clock: 0x00000007 - [ 10.865287] mmc1: sdhci: Timeout: 0x00000000 | Int stat: 0x00000000 - [ 10.871711] mmc1: sdhci: Int enab: 0x03ff008b | Sig enab: 0x03ff008b - [ 10.878134] mmc1: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000000 - [ 10.884557] mmc1: sdhci: Caps: 0x3de8c801 | Caps_1: 0x18002407 - [ 10.890981] mmc1: sdhci: Cmd: 0x00000c1a | Max curr: 0x00000000 - [ 10.897404] mmc1: sdhci: Resp[0]: 0x00000b00 | Resp[1]: 0x0075cf7f - [ 10.903828] mmc1: sdhci: Resp[2]: 0x32db7900 | Resp[3]: 0x00000900 - [ 10.910251] mmc1: sdhci: Host ctl2: 0x0000000b - [ 10.914682] mmc1: sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x00000000a2e90200 + .. note:: -Given below are the list of various workarounds that can be done in the -device tree node to get SD card working. The workarounds are ordered in -increasing order of reducing performance. + All the changes mentioned below, are to be done in the MMCSD device tree node + corresponding to the SD instance. This is usually the first (index starting + from zero) instance. -All the changes mentioned below, are to be done in the MMCSD device tree node -corresponding to the SD instance. This is usually the first (index starting -from zero) instance. + #. Restricting to a given speed mode -#. Restricting to a given speed mode + By default the kernel driver tries to enumerate an SD card in the highest supported + speed mode. Below is the order in which the driver tries to enumerate an SD card: - - By default the kernel driver tries to enumerate a SD card in the highest - supported speed mode. Given below is the order in which the driver - tries to enumerate a SD card + - SDR104 + - DDR50 + - SDR50 + - SD HS + - SD legacy - - SDR104 - - DDR50 - - SDR50 - - SD HS - - SD legacy + The **sdhci-caps-mask** can be added to the DT node to cap at a specific mode: - - These speed capabilites can be masked using device tree property - sdhci-caps-mask. + - Limit to DDR50: ``sdhci-caps-mask = <0x00000003 0x00000000>`` + - Limit to SD HS: ``sdhci-caps-mask = <0x00000007 0x00000000>`` + - Limit to SD legacy: ``sdhci-caps-mask = <0x00000007 0x00200000>`` - - Limit to DDR50: ``sdhci-caps-mask = <0x00000002 0x00000000>`` - - Limit to SDR50: ``sdhci-caps-mask = <0x00000006 0x00000000>`` - - Limit to SD HS: ``sdhci-caps-mask = <0x00000007 0x00000000>`` - - Limit to SD legacy: ``sdhci-caps-mask = <0x00000007 0x00200000>`` + The following is an example DT node with the added **sdhci-caps-mask**: - :: + .. code-block:: dts - &sdhci1 { - /* SD/MMC */ - vmmc-supply = <&vdd_mmc1>; - vqmmc-supply = <&vdd_sd_dv>; - pinctrl-names = "default"; - pinctrl-0 = <&main_mmc1_pins_default>; - ti,driver-strength-ohm = <50>; - disable-wp; - sdhci-caps-mask = <0x00000006 0x00000000>; /* Limiting to SDR50 speed mode */ - }; + &sdhci1 { + /* SD/MMC */ + vmmc-supply = <&vdd_mmc1>; + vqmmc-supply = <&vdd_sd_dv>; + pinctrl-names = "default"; + pinctrl-0 = <&main_mmc1_pins_default>; + ti,driver-strength-ohm = <50>; + disable-wp; + sdhci-caps-mask = <0x00000006 0x00000000>; /* Limiting to SDR50 speed mode */ + }; - - Limiting to SD HS speed mode can also be done by using the property - ``no-1-8-v``. This disable switching to 1.8V which is required for - UHS speed modes(SDR104, DDR50, SDR50) + Limiting to SD HS speed mode can also be done by using the property + **no-1-8-v**. This disables switching to 1.8V which is required for + UHS speed modes(SDR104, DDR50, SDR50, SDR25, SDR12): - :: + .. code-block:: dts - &sdhci1 { - /* SD/MMC */ - vmmc-supply = <&vdd_mmc1>; - vqmmc-supply = <&vdd_sd_dv>; - pinctrl-names = "default"; - pinctrl-0 = <&main_mmc1_pins_default>; - ti,driver-strength-ohm = <50>; - disable-wp; - no-1-8-v; /* disabling all the UHS modes */ - }; + &sdhci1 { + /* SD/MMC */ + vmmc-supply = <&vdd_mmc1>; + vqmmc-supply = <&vdd_sd_dv>; + pinctrl-names = "default"; + pinctrl-0 = <&main_mmc1_pins_default>; + ti,driver-strength-ohm = <50>; + disable-wp; + no-1-8-v; /* disabling all the UHS modes */ + }; + #. Reduce the bus width + + The SD interface supports a bus width of 4. It can be reduced to 1 by + changing the **bus-width** device tree property from 4 to 1. + + .. code-block:: diff + + diff --git a/arch/arm64/boot/dts/ti/k3-am62-main.dtsi b/arch/arm64/boot/dts/ti/k3-am62-main.dtsi + index 7bbfcb158842..2ef974f7206f 100644 + --- a/arch/arm64/boot/dts/ti/k3-am62-main.dtsi + +++ b/arch/arm64/boot/dts/ti/k3-am62-main.dtsi + @@ -424,7 +424,7 @@ + ti,itap-del-sel-sdr12 = <0x0>; + ti,itap-del-sel-sdr25 = <0x0>; + ti,clkbuf-sel = <0x7>; + - bus-width = <4>; + + bus-width = <1>; + }; + + sdhci2: mmc@fa20000 { + +| - -#. Reduce the bus width - - - The SD interface supports a bus width of 4. It can be reduced to 1 by - changing the ``bus-width`` device tree property from 4 to 1. - - :: - - diff --git a/arch/arm64/boot/dts/ti/k3-am62-main.dtsi b/arch/arm64/boot/dts/ti/k3-am62-main.dtsi - index 7bbfcb158842..2ef974f7206f 100644 - --- a/arch/arm64/boot/dts/ti/k3-am62-main.dtsi - +++ b/arch/arm64/boot/dts/ti/k3-am62-main.dtsi - @@ -424,7 +424,7 @@ - ti,itap-del-sel-sdr12 = <0x0>; - ti,itap-del-sel-sdr25 = <0x0>; - ti,clkbuf-sel = <0x7>; - - bus-width = <4>; - + bus-width = <1>; - }; - - sdhci2: mmc@fa20000 { +.. _create-partitions-in-emmc-uda-from-linux: + +Create software partitions in eMMC UDA +************************************** + +In eMMC, the User Data Area (UDA) HW partition is the primary storage +space generally used to flash the rootfs. To prepare the UDA, use +the :command:`fdisk` command. For ex: :samp:`fdisk /dev/mmcblkN` in +which **N** is 0 or 1. To find which integer is eMMC use the command +:command:`lsblk`, like so: + +.. code-block:: console + + root@:~# lsblk + NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS + mmcblk0 179:0 0 14.8G 0 disk + mmcblk0boot0 179:32 0 31.5M 1 disk + mmcblk0boot1 179:64 0 31.5M 1 disk + mmcblk1 179:96 0 14.8G 0 disk + |-mmcblk1p1 179:97 0 128M 0 part /run/media/boot-mmcblk1p1 + `-mmcblk1p2 179:98 0 1.9G 0 part / + +Where the eMMC will have hardware partitions :file:`mmcblkNboot0` +and :file:`mmcblkNboot1`. The :file:`mmcblkN` is the eMMC device. + +Now we use :samp:`fdisk /dev/mmcblk0` to create one software partition +in UDA. For documentation on using fdisk, please go to: +`fdisk how-to `__. + +.. _formatting-mmc-partition-from-linux: + +Formatting eMMC partitions from Linux +************************************* + +After creating a partition/s, the partition can be formated with +the :command:`mkfs` command. For ex: :samp:`mkfs -t ext4 /dev/mmcblkN` +where **mmcblkN** is the MMC device with the software partition to format. +The general syntax for formatting disk partitions in Linux is: + +.. code-block:: console + + mkfs [options] [-t type fs-options] device [size] + +For example, to format a partition in eMMC UDA to ext4 file system: + +.. code-block:: console + + root@:~# lsblk + NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS + mmcblk0 179:0 0 14.8G 0 disk + `-mmcblk0p1 179:1 0 14.8G 0 part /run/media/mmcblk0p1 + mmcblk0boot0 179:32 0 31.5M 1 disk + mmcblk0boot1 179:64 0 31.5M 1 disk + mmcblk1 179:96 0 14.8G 0 disk + |-mmcblk1p1 179:97 0 128M 0 part /run/media/boot-mmcblk1p1 + `-mmcblk1p2 179:98 0 8.8G 0 part / + root@:~# umount /run/media/mmcblk0p1 + [ 43.648532] EXT4-fs (mmcblk0p1): unmounting filesystem f8ecc7b8-ab1a-4240-ab4b-470d242c0539. + root@:~# mkfs -t ext4 /dev/mmcblk0p1 + mke2fs 1.47.0 (5-Feb-2023) + Discarding device blocks: done + Creating filesystem with 3884800 4k blocks and 972944 inodes + Filesystem UUID: 842929dd-4e57-47b6-afa1-c03abc3100b1 + Superblock backups stored on blocks: + 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208 + + Allocating group tables: done + Writing inode tables: done + Creating journal (16384 blocks): done + Writing superblocks and filesystem accounting information: done