一、eMMC介绍

eMMC (Embedded Multi Media Card）即嵌入式多媒体卡，是MMC协会订立、主要针对手机或平板电脑等产品的内嵌式存储器标准规格。eMMC在封装中集成了一个控制器，提供标准接口并管理闪存，简单描述如下：

eMMC=Nand Flash+控制器+标准封装

接口速度高达每秒400MBytes，eMMC具有快速、可升级的性能。同时其接口电压可以是1.8V或者是3.3V。

eMMC具有以下优势：

1.简化类手机产品存储器的设计。

2.更新速度快。

3.加速产品研发速度。

二、手动格式化eMMC操作

使用fdisk查看eMMC分区情况：

fdisk /dev/mmcblk1

Command (m for help): m        ---键入m 获取使用说明
Command action 
a toggle a bootable flag 
b edit bsd disklabel 
c toggle the dos compatibility flag 
d delete a partition 
l list known partition types 
m print this menu 
n add a new partition 
o create a new empty DOS partition table 
p print the partition table 
q quit without saving changes 
s create a new empty Sun disklabel 
t change a partition's system id 
u change display/entry units 
v verify the partition table 
w write table to disk and exit 
x extra functionality (experts only) 

接下来键入n，创建分区：n

Command (m for help): n                      ---键入n创建新的分区

接下来键入p，选择主分区：p

Select (default p): p               ---键入p创建主分区

Partition number (1-4, default 1): 1           ---键入分区号
First sector (2048-31116287, default 2048):              ---键入该分区的起始地址
2048 
Last sector, +sectors or +size{K,M,G} (2048-31116287, default 31116287): 258047           ---键入该分区的结束地址

以上第一个分区建立完成。

再创建第二个分区，键入n，创建分区：n

Command (m for help): n                      ---键入n创建新的分区

接下来键入p，选择主分区：p

Select (default p): p               ---键入p创建主分区

Partition number (1-4, default 1): 2           ---键入分区号
First sector (2048-31116287, default 2048):              ---键入该分区的起始地址
 258048           
Last sector, +sectors or +size{K,M,G} (2048-31116287, default 31116287): 7262208           ---键入该分区的结束地址

以上第二个分区建立完成。
键入p查看分区情况，发现还差设置启动分区、各个分区的文件类型通过p查看帮助，手动设置。
修改分区类型

Command (m for help): t            ---修改分区的系统类型
Partition number (1-4): 1             ---选择要修改的分区号

Hex code (type L to list codes): c             ---设置第一分区为W95 FAT32 (LBA)格式
Changed system type of partition 1 to c (W95 FAT32 (LBA)) 

最后，保存键入w：

Command (m for help): w                   ---保存分区设置并退出

查看系统分区情况

cat /proc/partitions

接下来将eMMC第二个分区格式化为ext4格式。

mkfs.ext4 /dev/mmcblk1p2

三、手动烧录eMMC步骤

我以SD卡为嵌入式启动卡启动，将SD卡文件拷贝到eMMC的分区。

root@linux-arm:/run/media# cd mmcblk1p1/
root@linux-arm:/run/media/mmcblk1p1# ls
root@linux-arm:/run/media/mmcblk1p1# cd ..
root@linux-arm:/run/media# mount /dev/mmcblk1p1 /run/media/mmcblk1p1
root@linux-arm:/run/media# ls
mmcblk0p1  mmcblk1p1
root@linux-arm:/run/media# cd mmcblk1p1/
root@linux-arm:/run/media/mmcblk1p1# ls
 MLO  'System Volume Information'u-boot.img
root@linux-arm:/run/media/mmcblk1p1# ls
 MLO  'System Volume Information'  u-boot.img
root@linux-arm:/run/media/mmcblk1p1# cd ..
root@linux-arm:/run/media# ls
mmcblk0p1  mmcblk1p1
root@linux-arm:/run/media# cd mmcblk1p1/
root@linux-arm:/run/media/mmcblk1p1# ls
 MLO  'System Volume Information'   u-boot.img
root@linux-arm:/run/media/mmcblk1p1# cp ../mmcblk0p1/* ./ -rdf
root@linux-arm:/run/media/mmcblk1p1# 


root@linux-arm:/run/media# mkdir mmcblk0p2/
root@linux-arm:/run/media# mkdir mmcblk1p2/
root@linux-arm:/run/media# mount /dev/mmcblk0p2 /run/media/mmcblk0p2

root@linux-arm:/run/media# 
root@linux-arm:/run/media# mount /dev/mmcblk1p2 /run/media/mmcblk1p2
root@linux-arm:/run/media# ls
mmcblk0p1  mmcblk0p2  mmcblk1p1  mmcblk1p2
root@linux-arm:/run/media# cp /run/me^Cmmcblk1p2/  -rdf

四、自动化脚本格式化和烧录eMMC

执行mkemmcboot.sh 完成格式化、烧录eMMC。

cat mkemmcboot.sh

#!/bin/bash
set -e

cur_dir=$(dirname $0)

. ${cur_dir}/utils.sh

erase_env

partition_emmc

${cur_dir}/mk_emmc_boot.sh

${cur_dir}/mk_emmc_fs.sh

cat utils.sh

# Description: Utility functions.
# Copyright 2019 Tronlong Elec. Tech. Co. Ltd. All Rights Reserved.

# Print error message with time.
err() {
    echo "[$(date +'%Y-%m-%dT%H:%M:%S%z')]: $@" >&2
}

# Check file existence.
function ck_file_ext() {
    if [[ ! -e $1 ]]; then
        err "ERROR! File not exist: $1"
        err "Abort, work not done!"
        exit 1
    fi
}

# Get MTD partition number
# Usage: MTD_NUM=$(get_mtd_num nand.env)
get_mtd_num() {
    num=$(cat /proc/mtd | grep $1 | awk -F ':' '{print $1}' | awk -F 'mtd' '{print $2}')
    if [[ -z "${num}" ]]; then
        err "ERROR! Get MTD partition number of $1 failed!"
        err "Abort, work not done!"
        exit 1
    fi
    echo ${num}
}

# Erase spi.env and nand.env
erase_env() {
    num=$(cat /proc/mtd | grep spi.env | awk -F ':' '{print $1}' | awk -F 'mtd' '{print $2}')
    if [[ ! -z "${num}" ]]; then
        flash_erase /dev/mtd${num} 0 0
        echo "spi.env erase done!"
    fi

    num=$(cat /proc/mtd | grep nand.env | awk -F ':' '{print $1}' | awk -F 'mtd' '{print $2}')
    if [[ ! -z "${num}" ]]; then
        flash_erase /dev/mtd${num} 0 0
        echo "nand.env erase done!"
    fi
}

partition_emmc() {
    echo "Partitioning /dev/mmcblk1..."

    # umount them in case mounted already.
    for i in $(cat /proc/mounts | grep /dev/mmcblk1p | awk '{print $1}'); do
        umount $i 2>/dev/null
    done

    emmc_dev=/dev/mmcblk1

    # Clear the head of emmc.
    dd if=/dev/zero of=${emmc_dev} bs=1024 count=1024

    # Get the partition information
    total_size=$(($(fdisk -s ${emmc_dev}) * 1024))
    total_cyln=$((total_size / 255 / 63 / 512))

    # Offsets. 128M for boot, 60% - 128M for rootfs, 40% for data.
    pc1_start=0
    pc1_end=$((128 * 1024 * 1024 / $((255 * 63 * 512)) ))   # 128M
    pc2_end=$((${total_cyln} * 3 / 5))

    parted -s ${emmc_dev} mklabel msdos
    parted -s ${emmc_dev} unit cyl mkpart primary fat32 -- 0 ${pc1_end}
    parted -s ${emmc_dev} set 1 boot on
    parted -s ${emmc_dev} unit cyl mkpart primary ext4 -- ${pc1_end} ${pc2_end}
    parted -s ${emmc_dev} unit cyl mkpart primary ext4 -- ${pc2_end} -2
    sleep 5    #FIXME Make sure partition emmc is finished
    echo "partition done!"
}

cat mk_emmc_boot.sh

#!/bin/bash
set -e
# Description: Burn boot files to eMMC.
# Copyright 2019 Tronlong Elec. Tech. Co. Ltd. All Rights Reserved.

# Load utility functions from utils.sh.
. $(dirname $0)/utils.sh

#### Defines ####

DEVICE=/dev/mmcblk1

#### Main Entrance ####

# Make sure device is exist.
dev1=$(ls -1 ${DEVICE} 2>/dev/null)
if [[ -z "${dev1}" ]]; then
    echo "ERROR: ${DEVICE} is not exist."
fi
# Make boot as FAT32 format.
echo "Formating boot partition..."
dev1=$(cat /proc/mounts | grep ${DEVICE}p1 | awk '{print $1}')
if [[ ! -z "${dev1}" ]]; then
    umount ${DEVICE}p1 # Umount boot in case mounted alraady.
fi
mkfs.vfat -F 32 -n BOOT ${DEVICE}p1
#FIXME Make sure format is finished
for ((i=0; $i<=100; i++))
do
    dev1=$(ls -1 ${DEVICE}p1 2>/dev/null)
    if [[ ! -z "${dev1}" ]]; then
        break;
    fi
    sleep 0.1
done
echo "Format done!"

# Mount boot partition.
boot_mp="/tmp/$$-boot"  # Mount points of boot partition.
if [[ ! -d ${boot_mp} ]]; then
    mkdir -p ${boot_mp}
fi
mount ${DEVICE}p1 ${boot_mp}

# Copy file to boot.
echo "Copying boot files to ${DEVICE}p1..."
cp -rf /run/media/mmcblk0p1/* ${boot_mp}

# Umount boot.
dev1=$(cat /proc/mounts | grep ${DEVICE}p1 | awk '{print $1}')
if [[ ! -z "${dev1}" ]]; then
    umount ${DEVICE}p1
fi

echo "Make eMMC boot partition done!"

cat mk_emmc_fs.sh

#!/bin/bash
set -e
# Description: Burn filesystem to eMMC. Make a data partition by the way.
# Copyright 2019 Tronlong Elec. Tech. Co. Ltd. All Rights Reserved.

# Load utility functions from utils.sh.
. $(dirname $0)/utils.sh

#### Defines ####

DEVICE=/dev/mmcblk1

#### Main Entrance ####

# Make rootfs and data partition as ext4 format.
echo "Formating rootfs and data partition..."
dev2=$(cat /proc/mounts | grep ${DEVICE}p2 | awk '{print $1}')
dev3=$(cat /proc/mounts | grep ${DEVICE}p3 | awk '{print $1}')
if [[ ! -z "${dev2}" ]]; then
    umount ${DEVICE}p2 # Umount in case mounted alraady.
fi
if [[ ! -z "${dev3}" ]]; then
    umount ${DEVICE}p3 # Umount in case mounted alraady.
fi
mkfs.ext4 -F -L rootfs ${DEVICE}p2
mkfs.ext4 -F -L data ${DEVICE}p3
#FIXME Make sure format is finished
for ((i=0; $i<=100; i++))
do
    dev2=$(ls -1 ${DEVICE}p2 2>/dev/null)
    dev3=$(ls -1 ${DEVICE}p3 2>/dev/null)
    if [[ ! -z "${dev2}" ]] && [[ ! -z "${dev3}" ]]; then
        break;
    fi
    sleep 0.1
done
echo "Format done!"

# Mount rootfs partition.
rootfs_mp="/tmp/$$-rootfs"  # Mount points of rootfs partition.
if [[ ! -d ${rootfs_mp} ]]; then
    mkdir -p ${rootfs_mp}
fi
mount ${DEVICE}p2 ${rootfs_mp}

# Copy file to rootfs from backup partition of SD.
echo "Copying rootfs files to ${DEVICE}p2..."
sd_p3_mp=$(df /dev/mmcblk0p3 | grep /dev/mmcblk0p3 | awk '{print $6}')
cp -rf ${sd_p3_mp}/. ${rootfs_mp}

# Umount boot.
dev2=$(cat /proc/mounts | grep ${DEVICE}p2 | awk '{print $1}')
if [[ ! -z "${dev2}" ]]; then
    umount ${DEVICE}p2
fi

echo "Make eMMC rootfs partition done!"

感谢阅读，祝君成功！
-by aiziyou