f8a1b33889
U-boot is intended to replace linux kernel in android boot image(ABL), and it's FIT payload to replace initramfs file. The boot process is similar to boot image with linux: - android bootloader (ABL) unpacks android boot image - ABL sets `linux,initrd-start property` in chosen node in unpacked FDT - ABL sets x0 register to FDT address, and passes control to u-boot - u-boot reads x0 register, and stores it in `prevbl_fdt_addr` env variable - u-boot reads `linux,initrd-start` property, and stores it in `prevbl_initrd_start_addr` In this way, u-boot bootcmd relies on `prevbl_initrd_start_addr` env variable, and boils down to `bootm $prevbl_initrd_start_addr`. If more control on boot process is desired, pack a boot script in FIT image, and put it to default configuration What done: - strip unneeded config options - add FIT image support - add framebuffer node, u-boot logo and video console - increase LMB_MAX_REGIONS, to store all linux dtb reserved memory regions - add linux kernel image header Uart driver causes hang, when u-boot is used in android boot image instead of linux. Temporary disable console driver, until investigated and fixed. Signed-off-by: Dzmitry Sankouski <dsankouski@gmail.com> Cc: Ramon Fried <rfried.dev@gmail.com>
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2.1 KiB
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84 lines
2.1 KiB
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.. SPDX-License-Identifier: GPL-2.0+
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.. sectionauthor:: Dzmitry Sankouski <dsankouski@gmail.com>
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Snapdragon 845
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================
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About this
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----------
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This document describes the information about Qualcomm Snapdragon 845
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supported boards and it's usage steps.
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SDM845 - hi-end qualcomm chip, introduced in late 2017.
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Mostly used in flagship phones and tablets of 2018.
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U-Boot can be used as a replacement for Qualcomm's original ABL (UEFI) bootloader.
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It is loaded as an Android boot image through ABL
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Installation
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------------
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Build
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^^^^^
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Setup ``CROSS_COMPILE`` for aarch64 and build U-Boot for your board::
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$ export CROSS_COMPILE=<aarch64 toolchain prefix>
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$ make <your board name here, see Boards section>_defconfig
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$ make
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This will build ``u-boot.bin`` in the configured output directory.
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Generate FIT image
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^^^^^^^^^^^^^^^^^^
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See doc/uImage.FIT for more details
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Pack android boot image
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^^^^^^^^^^^^^^^^^^^^^^^
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We'll assemble android boot image with ``u-boot.bin`` instead of linux kernel,
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and FIT image instead of ``initramfs``. Android bootloader expect gzipped kernel
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with appended dtb, so let's mimic linux to satisfy stock bootloader:
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- create dump dtb::
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workdir=/tmp/prepare_payload
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mkdir -p "$workdir"
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cd "$workdir"
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mock_dtb="$workdir"/payload_mock.dtb
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dtc -I dts -O dtb -o "$mock_dtb" << EOF
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/dts-v1/;
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/ {
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memory {
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/* We expect the bootloader to fill in the size */
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reg = <0 0 0 0>;
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};
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chosen { };
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};
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EOF
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- gzip u-boot ``gzip u-boot.bin``
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- append dtb to gzipped u-boot: ``cat u-boot.bin.gz "$mock_dtb" > u-boot.bin.gz-dtb``
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Now we've got everything to build android boot image:::
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mkbootimg --base 0x0 --kernel_offset 0x00008000 \
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--ramdisk_offset 0x02000000 --tags_offset 0x01e00000 \
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--pagesize 4096 --second_offset 0x00f00000 \
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--ramdisk "$fit_image" \
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--kernel u-boot.bin.gz-dtb \
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-o boot.img
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Flash image with your phone's flashing method.
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Boards
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------------
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starqlte
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^^^^^^^^^^^^
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The starqltechn is a production board for Samsung S9 (SM-G9600) phone,
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based on the Qualcomm SDM845 SoC.
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More information can be found on the `Samsung S9 page`_.
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.. _Samsung S9 page: https://en.wikipedia.org/wiki/Samsung_Galaxy_S9
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