Prepare Boot Medium
Input Files Required
Output Files Produced
- bootable SD card
Task Description
The following instructions are taken from the OMAPPedia wiki.
The following instructions assume a Linux system. Furthermore, most commands require root permissions. After completing this steps the SD card holds two partitions which can be read/written under Linux. Windows can - if at all - only access the FAT partition; but even this seems to depend on the card reader/driver used.
Insert SD card and figure out the corresponding device. The last lines of the dmesg output should tell you under which device file the inserted SD card is available in the system. dmesg
Warning: The following commands will use '/dev/sdX' to refer to the SD card device. Replace this with the actual device on your system. Executing the following commands on the wrong device may corrupt your data on other file systems. Also, all data on your SD card will be destroyed.
The fdisk utility does not seem to erase the first few bytes of the first sector in the card when the partition table is saved. Use dd to erase the first sector.
dd if=/dev/zero of=/dev/sdX bs=1024 count=1
Calculate the new_cylinders value
fdisk -l /dev/sdX
The output should look similar to this
Disk /dev/sdb: 8068 MB, 8068792320 bytes
249 heads, 62 sectors/track, 1020 cylinders, total 15759360 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/sdb doesn't contain a valid partition table
Look for the size of the device in bytes and calculate the new number of cylinders using the following formula, dropping all fractions:
new_cylinders =
/ 8225280
For the example output given above, we would write down new_cylinders = 8068792320 / 8225280 = 980.
Partition the SD card. We will create two partitions on the SD card. One 200 MB sized boot partition. And a second partition taking the remaining space on the SD card.
fdisk /dev/sdX
The dd command should have wiped all existing partition tables, if this is not the case, delete all existing partitions on the SD card.
Command (m for help):
Partition number (1-4): 1
Repeat this for all valid partitions numbers.Now configure the sectors, heads and cylinders of the SD card.
Command (m for help): x
Expert command (m for help): h
Number of heads (1-256, default 30): 255
Expert command (m for help): s
Number of sectors (1-63, default 29): 63
Expert command (m for help): c
Number of cylinders (1-1048576, default 2286):
Command (m for help): r
Now the actual partitions can be created
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-15759359, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-15759359, default 15759359): +200M
Command (m for help): n
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): p
Partition number (1-4, default 2): 2
First sector (411648-15759359, default 411648):
Using default value 411648
Last sector, +sectors or +size{K,M,G} (411648-15759359, default 15759359):
Using default value 15759359
Now, set the bootable flag and partition IDs
Command (m for help): a
Partition number (1-4): 1
Command (m for help): t
Partition number (1-4): 1
Hex code (type L to list codes): c
Changed system type of partition 1 to c (W95 FAT32 (LBA))
Command (m for help): t
Partition number (1-4): 2
Hex code (type L to list codes): 83
Check the new partition table and write the changes
Command (m for help): p
Disk /dev/sdb: 8068 MB, 8068792320 bytes
249 heads, 62 sectors/track, 1020 cylinders, total 15759360 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x920c958b
Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 411647 204800 c W95 FAT32 (LBA)
/dev/sdb2 411648 15759359 7673856 83 Linux
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.
Create file systems on the new partitions
mkfs.vfat -F 32 -n boot /dev/sdX1
mkfs.ext4 -L root /dev/sdX2
Mount the boot partition
mkdir -p /mnt/boot
mount /dev/sdX1 /mnt/boot
Copy the boot.bin or contents of the release archive to the SD card, e.g.
cp boot.bin /mnt/boot/
Unmount the SD card
umount /mnt/boot
The SD card can now be removed and transferred over to the target platform.