Partitioning a flash card

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{{Midgard article}}
 
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'''WARNING: Partitioning your flash card will delete all data of the card, so be sure to back up any important data to a computer or another flash card.'''
'''WARNING: Partitioning your flash card will delete all data of the card, so be sure to back up any important data to a computer or another flash card.'''
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'''Note:''' As of 4-28-2008 Penguinbait has made a deb package that automates all of this for you.  See http://www.internettablettalk.com/forums/showthread.php?t=19639  and http://www.internettablettalk.com/forums/showthread.php?t=20534
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For N900 see [[Repartitioning_the_flash]] and [[Changing the eMMC filesystem]]
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== Get root access ==
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See [[root access]].
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== Install the necessary packages and create partitions ==
== Install the necessary packages and create partitions ==
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'''Note:''' on the N800 and N810 the filesystem mounted under /media/mmc1 is the external media card and the internal card is mounted under /media/mmc2. The device that is mounted under /media/mmc1 is /dev/mmcblk1 and not mmcblk0 that is mounted under /media/mmc2. If you plan to format the external media card replace mmcblk0p with mmcblk1p.
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'''Note:''' on the N800 and N810 the filesystem numbering can be a little confusing.
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In Xterm on your tablet, '''as root''', run:
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* The '''external''' card device is /dev/mmcblk1 (mounted at /media/mmc1)
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* The '''internal''' card device is /dev/mmcblk0 (mounted at /media/mmc2)
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apt-get install e2fsprogs
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So if you plan to format the extern
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umount /media/mmc1
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  umount /media/mmc2
  umount /media/mmc2
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  sfdisk /dev/mmcblk0
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  sfdisk /dev/mmcblk0 << EOF
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  /dev/mmcblk0p1:1,15000,6
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  1,15000,6
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  /dev/mmcblk0p2:15001,,
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  15001,,
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  /dev/mmcblk0p3:
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  /dev/mmcblk0p4:
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EOF
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This will create two partitions in a 1GB flash card: the first one is VFAT (that's what number 6 means), and the second one is LINUX_83. The size of the first one is almost 480MB (that's the meaning of the 15000), and the second one is sized till the end of the card (that's what ,, means). Partitions three and four are empty. You may calculate your partitions based on my description, or read more about [http://linux.die.net/man/8/sfdisk sfdisk]. (Actually 15000 means cylinders, being each one of 32KB. So that 15000 cylinder x 32 KB/cylinder = 480MB. This means that 30000 cylinder x 32 KB/cylinder = 960MB). It will probably be easier to copy the example and just modify it slightly.
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'''** Note **''' "<< EOF" '' and'' "EOF" '' are required text if the commands are in a script file but are NOT entered if you are typing the commands into a terminal/shell. In the second case, sfdisk will require the Enter key be pressed, instead of blank lines, to sfdisk's prompts for any unused partitions. Keep pressing the Enter key until sfdisk has finished prompting for the partitions, then you will need to enter "y" to confirm you want to actually write the changes to the card.''
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This example will create two partitions in a 1GB flash card: the first one is FAT16 (that's what number 6 means), and the second one is the default Linux native partition (83). If you are using a card larger than 2GB, use "c" (FAT32 LBA) instead of "6". The size of the first one is almost 480MB (that's the meaning of the 15000), and the second one is sized till the end of the card (that's what ,, means). Partitions three and four are empty.
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The arguments for [http://linux.die.net/man/8/sfdisk sfdisk] are:
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* The device node to use for the partition
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* The start cylinder on the card
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* The end cylinder on the card (leave blank to have the partition go to the end of the disk)
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* The filesystem type ([http://www.win.tue.nl/~aeb/partitions/partition_types-1.html complete list])
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A cylinder is a 32KB block on a flash card, so 15,000 cylinders equates to 480,000KB (approx. 480MB).
== Format the partitions ==
== Format the partitions ==
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Once you have created the required partition table, you will need to initialise the filesystems.
Type as root:
Type as root:
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  shutdown -r now
  shutdown -r now
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After it reboots, then open Xterm and, '''as root''', run:
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After it reboots, then open Xterm and, as root, run:
  mke2fs /dev/mmcblk0p2
  mke2fs /dev/mmcblk0p2
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  insmod /mnt/initfs/lib/modules/$(uname -r)/mbcache.ko
  insmod /mnt/initfs/lib/modules/$(uname -r)/mbcache.ko
  insmod /mnt/initfs/lib/modules/$(uname -r)/ext2.ko
  insmod /mnt/initfs/lib/modules/$(uname -r)/ext2.ko
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mount /dev/mmcblk0p2 /media/mmc2
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(Note: /media/mmc2 will already have the VFAT partition mounted.  Perhaps we should create a directory in /media and mount to that instead?)
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[[Category:Users]]
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[[Category:Power users]]
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[[Category:Midgard wiki]]
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[[Category:Wiki page of the day]]
[[Category:Wiki page of the day]]
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[[Category:Power users]]

Latest revision as of 13:08, 10 August 2014

WARNING: Partitioning your flash card will delete all data of the card, so be sure to back up any important data to a computer or another flash card.

For N900 see Repartitioning_the_flash and Changing the eMMC filesystem

[edit] Install the necessary packages and create partitions

Note: on the N800 and N810 the filesystem numbering can be a little confusing.

  • The external card device is /dev/mmcblk1 (mounted at /media/mmc1)
  • The internal card device is /dev/mmcblk0 (mounted at /media/mmc2)

So if you plan to format the extern 

umount /media/mmc2
sfdisk /dev/mmcblk0 << EOF
1,15000,6
15001,,


EOF

** Note ** "<< EOF" and "EOF" are required text if the commands are in a script file but are NOT entered if you are typing the commands into a terminal/shell. In the second case, sfdisk will require the Enter key be pressed, instead of blank lines, to sfdisk's prompts for any unused partitions. Keep pressing the Enter key until sfdisk has finished prompting for the partitions, then you will need to enter "y" to confirm you want to actually write the changes to the card.

This example will create two partitions in a 1GB flash card: the first one is FAT16 (that's what number 6 means), and the second one is the default Linux native partition (83). If you are using a card larger than 2GB, use "c" (FAT32 LBA) instead of "6". The size of the first one is almost 480MB (that's the meaning of the 15000), and the second one is sized till the end of the card (that's what ,, means). Partitions three and four are empty.

The arguments for sfdisk are:

  • The device node to use for the partition
  • The start cylinder on the card
  • The end cylinder on the card (leave blank to have the partition go to the end of the disk)
  • The filesystem type (complete list)

A cylinder is a 32KB block on a flash card, so 15,000 cylinders equates to 480,000KB (approx. 480MB).

[edit] Format the partitions

Once you have created the required partition table, you will need to initialise the filesystems.

Type as root: 

mkdosfs /dev/mmcblk0p1
shutdown -r now

After it reboots, then open Xterm and, as root, run: 

mke2fs /dev/mmcblk0p2
shutdown -r now

[edit] Mounting the partitions

The VFAT partition will be mounted by the system automagically at start-up. To mount the EXT2 partition we need to load the kernel modules, so open Xterm and, as root, type: 

insmod /mnt/initfs/lib/modules/$(uname -r)/mbcache.ko
insmod /mnt/initfs/lib/modules/$(uname -r)/ext2.ko
mount /dev/mmcblk0p2 /media/mmc2

(Note: /media/mmc2 will already have the VFAT partition mounted. Perhaps we should create a directory in /media and mount to that instead?)

Retrieved from "http://wiki.maemo.org/Partitioning_a_flash_card"