Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 2/14/2023
Public

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16.5.12.3.2. Booting Removable MMC4.3, MMC4.4 and MMC4.41 Cards

For removable MMC4.3, MMC4.4 and MMC4.41 cards, the software driver must perform the following steps:
  1. Discover the card as described in Enumerated Card Stack.
  2. Read the EXT_CSD register of the card and examine the following fields:
    • BOOT_PARTITION_ENABLE
    • BOOT_SIZE_MULT
    • BOOT_INFO
  3. If necessary, the software can manipulate the boot information in the card.
    Note: For more information, refer to “Access to Boot Partition” in the following specifications available on the JEDEC website:
    • JEDEC Standard No. 84‑A441
    • JEDEC Standard No. 84‑A44
    • JEDEC Standard No. JESD84‑A43
  4. If the host processor needs to perform a boot operation at the next power‑up cycle, it can manipulate the EXT_CSD register contents by using a SWITCH_FUNC command.
  5. After this step, the software driver must power down the card by writing to the pwren register.
  6. From here on, use the same steps as in Alternative Boot Operation for eMMC Card Devices.