How to create a bootlable SD card for Raspberry pi BeagleBone using Disk Utility

By | May 15, 2016

In this post we will see the procedure to create a bootable SD card using Disk Utilities GUI or simply Disks.

In a SD card booting, first step is to create a bootable SD card. SD card needs to be partitioned based on the requirement and each partition will be formatted with particular file system.

In most of cases, a bootable SD card contains two major partitions

  1. Primary or Boot partition
  2. Secondary or Root File system
  3. Backup (Optional)

Normally, primary partition is formatted to FAT file format ( If boot Rom supported ) and contains fist stage bootloader,  second stage bootloader, boot args, Kernel, device tree, etc..

Secondary partition is formatted EXT4, EXT3, EXT2 etc .. and contains a root filesystem , simply rootfs.

SD card enumeration in Linux:

SD card enumeration varies based on the hardware medium used to connect to host computer.

External USB card reader :

If you are using a external card reader, SD card enumerates as a ‘sdX’ device. X shall be ‘a’, ‘b’, ‘c’, ‘d’ and so on. To know the exact device file name, you can use below mentioned command.

  • Insert card reader with memory card
  • Check the dmesg log now
 $ dmesg | tail

You will see similar log message as shown below

[37438.031052] usb 1-1: USB disconnect, device number 3
[37440.172608] usb 1-1: new high-speed USB device number 4 using ehci-pci
[37440.461861] usb 1-1: New USB device found, idVendor=1908, idProduct=0226
[37440.461875] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[37440.468083] usb-storage 1-1:1.0: USB Mass Storage device detected
[37440.470519] scsi host35: usb-storage 1-1:1.0
[37441.473634] scsi 35:0:0:0: Direct-Access Generic Mass-Storage 1.11 PQ: 0 ANSI: 2
[37441.474411] sd 35:0:0:0: Attached scsi generic sg2 type 0
[37442.223122] sd 35:0:0:0: [sdb] 31116288 512-byte logical blocks: (15.9 GB/14.8 GiB)
[37442.231127] sd 35:0:0:0: [sdb] Write Protect is off
[37442.231139] sd 35:0:0:0: [sdb] Mode Sense: 03 00 00 00
[37442.238237] sd 35:0:0:0: [sdb] No Caching mode page found
[37442.238425] sd 35:0:0:0: [sdb] Assuming drive cache: write through
[37442.280981] sdb: sdb1
[37442.314386] sd 35:0:0:0: [sdb] Attached SCSI removable disk
[37443.120217] FAT-fs (sdb1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.

From the above log [ sdb: sdb1 ], my SD card detected as ‘sdb’ and it has one partition ‘sdb1’.

SD/MMC card slot :

Identifying the SD card device node is kind of easy compared to External card reader device node. The name of the device node is some thing like mmcblkXpY.

Where X is the SD/MMC card device number and Y is the device’s partition number.

After inserting the SD card you can run below commands to identify the device node.

$ dmesg | tail


$ ls /dev/mmc*


Steps to create a Bootable SD card in Ubuntu:

Step 1: Click on “Search your compute .. ” or simply press “Windows” button

Step 2: Type Disks and click on it.

Ubuntu-Format-SD card-step01Step 1 : Or simply type “gnome-disks” in your terminal. You will be presented with “Disks” GUI

Ubuntu-Format-SD card-step2

In the GUI, under the “Devices” identify your SD card and click on it.

Step 2: Unmount the SD card by clicking “Unmount the filesystem”

Ubuntu-Format-SD card-step3

Step 3 : click on “Delete partition” a “minus” symbol

Ubuntu-Format-SD card-step4

Step 4: You will be presented with a popup. Click on Delete.

This step deletes entire memory card data, so take backup if necessary. Also make sure that you have not selected a wrong computer partition or memory device.

Ubuntu-Format-SD card-step5

Step 5: You should see a [+] symbol.

Ubuntu-Format-SD card-step6

Step 6 : Now, click on [+] symbol to create a new partition in the SD card. You will be presented with “Create Partition” popup.

Ubuntu-Format-SD card-step7

Step 7 : In this step we will be creating primary partition.

Enter Partition Size : 256 MB ( More than enough for a primary partition)

Erase : Don’t overwrite existing data (Other option if you have enough time)

Type : Select FAT ( Maybe, you can check device data sheet for supported filesystem )

Name: BOOT (is reasonable)

Click on “Create”.

Ubuntu-Format-SD card-step8

Step 8: After step-5, GUI will be shown as below.

BOOT Partition 1 256 MB FAT and Free Space

Ubuntu-Format-SD card-step9

Step 9 : In this step we will create a root filesystem partition.

Now select “Free Space” and click on [+]. You will get a “create Partition” popup.

Partition Size : 2048 MB (Change based on requirement)

Erase: Don’t overwrite existing data

Type : EXT4 (Depends on Kernel configuration)

Name : RootFS

and click on Create.

Ubuntu-Format-SD card-step10


Step 10: Select primary partition and click on “more actions ” and select “Edit Partition”

Ubuntu-Format-SD card-step11

Step 11 : Final step, now select Bootable and Click on “Change”

Ubuntu-Format-SD card-step12


Now, bootable SD card is ready. Copy the required components to the respective folders and boot.

Good day

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