三月 26, 2011

Linux Boot Disk Format

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本文介绍了如何为DevKit8000格式化SD卡,以便通过SD卡启动安装在SD卡中的Linux操作系统!


How to create a dual-partition card for DevKit8000 to boot Linux from first partition and have root file system at second partition.

一、Introduction

This guide is meant for those looking to create a dual-partition card, booting from a FAT partition that can be read by the OMAP3 ROM bootloader and Linux/Windows, then utilizing an ext3 partition for the Linux root file system.

二、Details

Text marked with [] shows user input.

1Determine which device the SD Card Reader is on your system

Plug the SD Card into the SD Card Reader and then plug the SD Card Reader into your system. After doing that, do the following to determine which device it is on your system.

$ [dmesg | tail]

[ 6854.215650] sd 7:0:0:0: [sdc] Mode Sense: 0b 00 00 08 [ 6854.215653] sd 7:0:0:0: [sdc] Assuming drive cache: write through

[ 6854.215659] sdc: sdc1

[ 6854.218079] sd 7:0:0:0: [sdc] Attached SCSI removable disk

[ 6854.218135] sd 7:0:0:0: Attached scsi generic sg2 type 0

In this case, it shows up as /dev/sdc (note sdc inside the square brackets above).

2Check to see if the automounter has mounted the SD Card

Note there may be more than one partition (only one shown in the example below).

$ [df -h]

Filesystem Size Used Avail Use% Mounted on

/dev/sdc1 400M 94M 307M 24% /media/disk

Note the “Mounted on” field in the above and use that name in the umount commands below.

3If so, unmount it

$ [umount /media/disk]

4Start fdisk

Be sure to choose the whole device (/dev/sdc), not a single partition (/dev/sdc1).

$ [sudo fdisk /dev/sdc]

5Print the partition record

So you know your starting point. Make sure to write down the number of bytes on the card (in this example, 2021654528).

Command (m for help): [p]

Disk /dev/sdc: 2021 MB, 2021654528 bytes

255 heads, 63 sectors/track, 245 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System

/dev/sdc1 * 1 246 1974240+ c W95 FAT32 (LBA)

Partition 1 has different physical/logical endings:

phys=(244, 254, 63) logical=(245, 200, 19)

6Delete any partitions that are there already

Command (m for help): [d]

Selected partition 1

7Set the Geometry of the SD Card

If the print out above does not show 255 heads, 63 sectors/track, then do the following expert mode steps to redo the SD Card:

1)、Go into expert mode.

Command (m for help): [x]

2)、Set the number of heads to 255.

Expert Command (m for help): [h]

Number of heads (1-256, default xxx): [255]

3Set the number of sectors to 63.

Expert Command (m for help): [s]

Number of sectors (1-63, default xxx): [63]

4Now Calculate the number of Cylinders for your SD Card.

#cylinders = FLOOR (the number of Bytes on the SD Card (from above) / 255 / 63 / 512 )

So for this example: 2021654528 / 255 / 63 / 512 = 245.79. So we use 245 (i.e. truncate, don’t round).

5Set the number of cylinders to the number calculated.

Expert Command (m for help): [c]

Number of cylinders (1-256, default xxx): [enter the number you calculated]

6Return to Normal mode.

Expert Command (m for help): [r]

8Print the partition record to check your work

Command (m for help): [p]

Disk /dev/sdc: 2021 MB, 2021654528 bytes

255 heads, 63 sectors/track, 245 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System

9Create the FAT32 partition for booting and transferring files from Windows

Command (m for help): [n]

Command action

e extended

p primary partition (1-4)

[p]

Partition number (1-4): [1]

First cylinder (1-245, default 1): [(press Enter)]

Using default value 1

Last cylinder or +size or +sizeM or +sizeK (1-61, default 61): [+5]

Command (m for help): [t]

Selected partition 1

Hex code (type L to list codes): [c]

Changed system type of partition 1 to c (W95 FAT32 (LBA))

10Mark it as bootable

Command (m for help): [a]

Partition number (1-4): [1]

11Create the Linux partition for the root file system

Command (m for help): [n]

Command action

e extended

p primary partition (1-4)

[p]

Partition number (1-4): [2]

First cylinder (7-61, default 7): [(press Enter)]

Using default value 52

Last cylinder or +size or +sizeM or +sizeK (7-61, default 61): [(press Enter)]

Using default value 245

12Print to Check Your Work

Command (m for help): [p]

Disk /dev/sdc: 2021 MB, 2021654528 bytes

255 heads, 63 sectors/track, 245 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System

/dev/sdc1 * 1 6 409626 c W95 FAT32 (LBA)

/dev/sdc2 7 61 1558305 83 Linux

13Save the new partition records on the SD Card

This is an important step. All the work up to now has been temporary.

Command (m for help): [w]

The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.

The kernel still uses the old table.

The new table will be used at the next reboot.

WARNING: If you have created or modified any DOS 6.x

partitions, please see the fdisk manual page for additional

information.

Syncing disks.

14Format the partitions

The two partitions are given the volume names LABEL1 and LABEL2 by these commands. You can substitute your own volume labels.

$ [sudo mkfs.msdos -F 32 /dev/sdc1 -n LABEL1]

mkfs.msdos 2.11 (12 Mar 2005)

$ [sudo mkfs.ext3 -L LABEL2 /dev/sdc2]

mke2fs 1.40-WIP (14-Nov-2006)

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

195072 inodes, 389576 blocks

19478 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=402653184

12 block groups

32768 blocks per group, 32768 fragments per group

16256 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912

Writing inode tables: done

Creating journal (8192 blocks): done

Writing superblocks and filesystem accounting information:

 

 

 

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