mirror of
https://github.com/AsahiLinux/u-boot
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95 lines
3.1 KiB
ReStructuredText
95 lines
3.1 KiB
ReStructuredText
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.. SPDX-License-Identifier: GPL-2.0+
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U-Boot for the ASUS/Google Nexus 7 (2012)
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=========================================
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``DISCLAMER!`` Moving your ASUS/Google Nexus 7 (2012) to use
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U-Boot assumes replacement of the vendor ASUS bootloader. Vendor
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android firmwares will no longer be able to run on the device.
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This replacement IS reversible.
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Quick Start
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-----------
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- Build U-Boot
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- Pack U-Boot into repart-block
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- Flash repart-block into the eMMC
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- Boot
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- Self Upgrading
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Build U-Boot
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------------
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Device support is implemented by applying config fragment to a generic
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board defconfig. Valid fragments are ``grouper_E1565.config``,
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``grouper_PM269.config`` and ``tilapia.config``.
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.. code-block:: bash
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$ export CROSS_COMPILE=arm-linux-gnueabi-
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$ make grouper_common_defconfig grouper_E1565.config # For maxim based grouper
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$ make
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After the build succeeds, you will obtain the final ``u-boot-dtb-tegra.bin``
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image, ready for flashing (but check the next section for additional
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adjustments).
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Pack U-Boot into repar-block
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----------------------------
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``DISCLAMER!`` All questions related to re-crypt work should be asked
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in re-crypt repo issues. NOT HERE!
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re-crypt is a small script which packs ``u-boot-dtb-tegra.bin`` in
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form usable by device. This process is required only on the first
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installation or to recover the device in case of a failed update.
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You need to know your tablet's individual SBK to continue.
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.. code-block:: bash
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$ git clone https://github.com/clamor-s/re-crypt.git
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$ cd re-crypt # place your u-boot-dtb-regra.bin here
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$ ./re-crypt.sh -d grouper -k deadbeefdeadc0dedeadd00dfee1dead
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Script will produce you a ``repart-block.bin`` ready to flash.
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Flash repart-block into the eMMC
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--------------------------------
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``DISCLAMER!`` All questions related to NvFlash should be asked
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in the proper place. NOT HERE! Flashing repart-block will erase
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all your eMMC, so make a backup before!
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``repart-block.bin`` contains BCT and bootloader in encrypted state
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in form which can just be written RAW at the start of eMMC.
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.. code-block:: bash
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$ wheelie --blob blob.bin
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$ nvflash --resume --rawdevicewrite 0 1024 repart-block.bin
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Boot
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----
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After flashing ``repart-block.bin`` the device should reboot and turn
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itself off. This is normal behavior if no boot configuration is
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found.
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To boot Linux, U-Boot will look for an ``extlinux.conf`` configuration
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on eMMC. Additionally if Volume Down button is pressed while booting
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device will enter bootmenu. Bootmenu contains entries to mount eMMC as
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mass storage, fastboot, reboot, reboot RCM, poweroff, enter U-Boot
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console and update bootloader (check next chapter).
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Flashing ``repart-block.bin`` eliminates vendor restriction on eMMC
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and allows the user to use/partition it in any way the user desires.
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Self Upgrading
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--------------
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Place your ``u-boot-dtb-tegra.bin`` on the first partition of the
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eMMC (using ability of u-boot to mount it). Enter bootmenu, choose
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update bootloader option with Power button and U-Boot should update
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itself. Once the process is completed, U-Boot will ask to press any
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button to reboot.
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