.. include:: /keyword.rst

===============
Serial NOR Boot
===============

|IOT-YOCTO| now provides reference support for booting from Serial NOR Flash used to store the bootloader. Others such as kernel and rootfs are stored in the storage device. The Genio EVK does not have on-board Serial NOR Flash, so this section is based on reworked EVK boards for Serial NOR boot demonstration.

.. contents:: Sections
    :local:
    :depth: 2

Build Packages
--------------

Please assign the ``MACHINE`` config variable to build the packages for the Genio EVK board:

.. tabs::

   .. group-tab:: |G510-EVK|

    The bootloader will boot from Serial NOR Flash and then boot the kernel and rootfs from eMMC.
      .. prompt:: bash $ auto

         $ export MACHINE=genio-510-evk-norboot
         $ bitbake rity-demo-image

   .. group-tab:: |G700-EVK|

    The bootloader will boot from Serial NOR Flash and then boot the kernel and rootfs from eMMC.
      .. prompt:: bash $ auto

         $ export MACHINE=genio-700-evk-norboot
         $ bitbake rity-demo-image

   .. group-tab:: |G1200-EVK|

    The bootloader will boot from Serial NOR Flash and then boot the kernel and rootfs from UFS.
      .. prompt:: bash $ auto

         $ export MACHINE=genio-1200-evk-norboot-ufs
         $ bitbake rity-demo-image


Serial NOR Flash Layout
-----------------------

We store the bootloader defined as **firmware** category in Serial NOR Flash. The following table describes the layout scheme for the Genio EVK board using Serial NOR Flash.

.. csv-table:: Serial NOR Flash Layout on Genio EVK Boards
   :file: /_asset/tables/genio-norflash-layout.csv
   :header-rows: 1

Layout Configurations
----------------------

|IOT-YOCTO| provides a simple solution for adjusting the size and layout of Serial NOR Flash. Users can find the layout definition in the download agent (lk) and U-Boot for customization. The following example describes the ``nor_bl2`` layout definition for |G1200-EVK| :

* `target.h <https://gitlab.com/mediatek/aiot/nda/lk/-/blob/main/target/mt8395-evk-norboot-ufs/include/target/target.h>`_ in the download agent (lk) for |G1200-EVK| :

.. prompt:: bash $ auto

        #define NOR_PARTITIONS_INDEX0 "nor_bl2"

* `genio_1200_evk_ufs_qspi_defconfig <https://gitlab.com/mediatek/aiot/bsp/u-boot/-/blob/mtk-v2022.10/configs/genio_1200_evk_ufs_qspi_defconfig>`_ in the U-Boot for |G1200-EVK|:

.. prompt:: bash $ auto

        CONFIG_MTDPARTS_DEFAULT="mtdparts=nor0:4m(nor_bl2),..."

In this example, users can find the 4MB region size and the offset of ``nor_bl2`` in the layout definition for Serial NOR Flash. In addition, users can also customize the layout definition according to their product requirements.

.. note::

    Please make sure the layout definition of the download agent (lk) and U-Boot are the same, otherwise the system will fail to boot.