.. 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.

|G520-G720-EVK| provides on-board Serial NOR Flash storage, and the Boot ROM can be configured
to use different boot storage via external pin strapping. Make sure to set ``Boot Selection``
switches as shown in :ref:`Get Started <g520g720-boot-selection>` guide.

Other Genio EVK boards do not have on-board Serial NOR Flash,
so a reworked EVK board is required 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

   .. group-tab:: |G520-G720-EVK| NOR Boot

      The bootloader will boot from Serial NOR Flash and then boot the kernel and rootfs from UFS.
      Make sure to set ``Boot Selection`` switches as shown in :ref:`Get Started <g520g720-boot-selection>` guide.

      .. prompt:: bash $ auto

         $ export MACHINE=genio-720-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.