一、目的：嵌入式开发板，通过emmc上的内核文件加载启动linux操作系统，以及存放其他程序文件。需要将所需文件先写入emmc中。
二、总体步骤是：uboot启动后，进入linux下，将emmc分区并格式化，uboot下支持fat和ext2的格式，这里用fat格式，并挂载，然后放入所需要的文件。这样重启后，进入uboot下，将emmc中的文件load到内存中运行。
三、uboot下emmc内容烧写（拷贝）步骤：
1、uboot启动后，输入mmc info有mmc的相关信息
2、通过tftp或其他方式启动linux
3、linux启动后，输入fdisk -l能看到/dev/mmcblk0的信息
4、linux下用fdisk命令对mmc分区，格式化
#fdisk /dev/mmcblk0
fdisk命令都是非常简单的。
WARNING: DOS-compatible mode is deprecated. It's strongly
recommended to
switch off the mode (command 'c') and change display units
to
sectors (command 'u').
Command (m for help): m
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)
先P，看看sd卡的分区现状。
然后d，删除原分区
n，创建分区
Command (m for help): n
Command action
e extended
p primary partition
(1-4)
p
Partition number (1-4): 1
First cylinder (1-62528, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-62528, default
62528): +1500M
t，指定分区类型，
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): L
0
Empty
24 NEC
DOS
81 Minix / old Lin bf
Solaris
1
FAT12
39 Plan
9
82 Linux swap / So c1 DRDOS/sec
(FAT-
2 XENIX
root
3c PartitionMagic
83
Linux
c4 DRDOS/sec (FAT-
3 XENIX
usr
40 Venix
80286
84 OS/2 hidden C:
c6 DRDOS/sec (FAT-
4 FAT16
<32M
41 PPC PReP
Boot 85 Linux
extended c7
Syrinx
5
Extended
42
SFS
86 NTFS volume set da Non-FS
data
6
FAT16
4d
QNX4.x
87 NTFS volume set db CP/M /
CTOS / .
7
HPFS/NTFS
4e QNX4.x 2nd part 88 Linux
plaintext de Dell
Utility
8
AIX
4f QNX4.x 3rd part 8e Linux
LVM
df
BootIt
9 AIX
bootable
50 OnTrack
DM
93
Amoeba
e1 DOS
access
a OS/2 Boot Manag 51 OnTrack
DM6 Aux 94 Amoeba
BBT
e3 DOS
R/O
b W95
FAT32
52
CP/M
9f
BSD/OS
e4
SpeedStor
c W95 FAT32 (LBA) 53 OnTrack
DM6 Aux a0 IBM Thinkpad hi eb
BeOS
fs
e W95 FAT16 (LBA) 54
OnTrackDM6
a5
FreeBSD
ee
GPT
f W95 Ext'd (LBA) 55
EZ-Drive
a6
OpenBSD
ef EFI (FAT-12/16/
10
OPUS
56 Golden
Bow
a7
NeXTSTEP
f0 Linux/PA-RISC b
11 Hidden
FAT12
5c Priam
Edisk
a8 Darwin
UFS
f1
SpeedStor
12 Compaq diagnost 61
SpeedStor
a9
NetBSD
f4
SpeedStor
14 Hidden FAT16 <3 63 GNU
HURD or Sys ab Darwin
boot
f2 DOS
secondary
16 Hidden
FAT16
64 Novell Netware
af HFS /
HFS+
fb VMware
VMFS
17 Hidden HPFS/NTF 65 Novell
Netware b7 BSDI
fs
fc VMware VMKCORE
18 AST SmartSleep
70 DiskSecure Mult b8 BSDI
swap
fd Linux raid auto
1b Hidden W95 FAT3 75
PC/IX
bb Boot Wizard hid fe
LANstep
1c Hidden W95 FAT3 80 Old
Minix
be Solaris
boot
ff
BBT
1e Hidden W95 FAT1
Hex code (type L to list codes): 6
Changed system type of partition 1 to 6 (FAT16)
这样就分好了第一个分区，并且指定了分区为fat16
好了，看看成果。
Command (m for help): p
Disk /dev/mmcblk0: 2048 MB, 2048917504 bytes
4 heads, 16 sectors/track, 62528 cylinders
Units = cylinders of 64 * 512 = 32768 bytes
Sector size (logical/physical): 512 bytes / 512
bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x6f20736b
Device
Boot
Start
End
Blocks Id
System
/dev/mmcblk0p1
1
48001
1536024
6 FAT16
/
好了，把分区信息写入磁盘。
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: If you have created or modified any DOS
6.x
partitions, please see the fdisk manual page for
additional
information.
Syncing disks.
下面开始格式化。
首先是fat16分区
#mkdosfs
/dev/mmcblk0p1
看一下格式化后的
~ # fdisk
-l
Disk /dev/mmcblk0: 1920 MB, 1920991232 bytes
4 heads, 16 sectors/track, 58624 cylinders
Units = cylinders of 64 * 512 = 32768 bytes
Device
Boot
Start
End
Blocks Id System
/dev/mmcblk0p1
1
58624
1875960 6 FAT16
把emmc挂载在一目录下
~ # mount /dev/mmcblk0p1 /vm
1
58624
1875960 6 FAT16
这样就可以将文件拷贝到/vm下，这里新建了一txt文件，并输入内容，重启后在uboot下查看emmc中是否有改文件。
~ # cd vm
/vm # ls
/vm # vi a.txt
11111111111111111111111111111111111111111111
0000000000000000000000000000000000000000000
11111111111111111111111111111111111111111111
00000000000000000000000000000000000000000000
#reboot
重启后进入uboot下，查看mmc设备
Octeon# mmc list
Octeon MMC/SD0: 0
用fatls命令查看mmc下的文件信息，可以看到有linux下建的a.txt文件
Octeon #fatls mmc 0
181 a.txt
1 file(s), 0 dir(s)
将mmc中a.txt拷贝到内存中查看内容
先看一下原来内存的信息
Octeon# md 30000000
30000000: 00000000 00000000 00000000
5f800000
............_...
30000010: 00000000 00000000 00000000
00000000
................
30000020: 00000000 00000000 00000000
00000000
................
30000030: 00000000 00000000 00000000
00000000
................
30000040: 00000000 00000000 00000000
00000000
................
30000050: 00000000 00000000 00000000
00000000
................
30000060: 00000000 00000000 00000000
00000000
................
30000070: 00000000 00000000 00000000
00000000
................
30000080: 00000000 00000000 00000000
00000000
................
30000090: 00000000 00000000 00000000
00000000
................
300000a0: 00000000 00000000 00000000
00000000
................
300000b0: 00000000 00000000 00000000
00000000
................
300000c0: 00000000 00000000 00000000
00000000
................
300000d0: 00000000 00000000 00000000
00000000
................
300000e0: 00000000 00000000 00000000
00000000
................
300000f0: 00000000 00000000 00000000
00000000
................
将mmc中a.txt load到内存中
Octeon# fatload mmc 0 30000000 a.txt
reading a.txt
181 bytes read
查看内存信息，可以看到就是a.txt的内容，说明emmc内容写入成功 。
Octeon# md 30000000
30000000: 31313131 31313131 31313131
31313131
1111111111111111
30000010: 31313131 31313131 31313131
31313131
1111111111111111
30000020: 31313131 31313131 31313131
0a303030
111111111111.000
30000030: 30303030 30303030 30303030
30303030
0000000000000000
30000040: 30303030 30303030 30303030
30303030
0000000000000000
30000050: 30303030 30303030 0a313131
31313131
00000000.1111111
30000060: 31313131 31313131 31313131
31313131
1111111111111111
30000070: 31313131 31313131 31313131
31313131
1111111111111111
30000080: 31313131 310a3030 30303030
30303030
11111.0000000000
30000090: 30303030 30303030 30303030
30303030
0000000000000000
300000a0: 30303030 30303030 30303030
30303030
0000000000000000
300000b0: 30300a0a 0a000000 00000000
00000000
00..............
300000c0: 00000000 00000000 00000000
00000000
................
300000d0: 00000000 00000000 00000000
00000000
................
300000e0: 00000000 00000000 00000000
00000000
................
300000f0: 00000000 00000000 00000000
00000000
................