Sd card format

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A bootable SD card should have the following format:

  • First 512 bytes is the partition table.
  • The ROM (primary bootloader) looks for a file with a correct DCD signature 1k into the SD card. Place your u-boot / SPL 1k into the card.
  • The location of a tertiary bootloader (needed if using SPL u-boot, not otherwise) is determined by the secondary bootloader
  • The location of a Linux kernel is usually 1MB into the SD card. This can be changed in u-boot.
  • The root filesystem is located somewhere on the SD card, and mounted depending on the rootfs kernel parameter (passed from u-boot).

To place a u-boot.bin into SD card, one can use the command:

  1. dd if=u-boot.imx of=/dev/DEVICE bs=1k seek=1 oflag=dsync