Qualcomm generic boards

About this

This document describes how to build and run U-Boot for Qualcomm generic boards. Right now the generic target supports the Snapdragon 845 SoC, however it’s expected to support more SoCs going forward.

SDM845 - high-end qualcomm chip, introduced in late 2017. Mostly used in flagship phones and tablets of 2018.

The current boot flow support loading u-boot as an Android boot image via Qualcomm’s UEFI-based ABL (Android) Bootloader. The DTB used by U-Boot will be appended to the U-Boot image the same way as when booting Linux. U-Boot will then retrieve the DTB during init. This way the memory layout and KASLR offset will be populated by ABL.

Installation

Build

$ ./tools/buildman/buildman -o .output qcom

This will build .output/u-boot-nodtb.bin using the qcom_defconfig.

Generate FIT image (optional)

See doc/uImage.FIT for more details

Pack android boot image

We’ll assemble android boot image with u-boot-nodtb.bin instead of linux kernel, and FIT image instead of initramfs. Android bootloader expect gzipped kernel with appended dtb, so let’s mimic linux to satisfy stock bootloader.

Boards

starqlte

The starqltechn is a production board for Samsung S9 (SM-G9600) phone, based on the Qualcomm SDM845 SoC.

This device is supported by the common qcom_defconfig.

The DTB is called “sdm845-samsung-starqltechn.dtb”

More information can be found on the Samsung S9 page.

dragonboard845c

The dragonboard845c is a Qualcomm Robotics RB3 Development Platform, based on the Qualcomm SDM845 SoC.

This device is supported by the common qcom_defconfig

The DTB is called “sdm845-db845c.dtb”

More information can be found on the DragonBoard 845c page.

qcs404-evb

The QCS404 EvB is a Qualcomm Development Platform, based on the Qualcomm QCS404 SoC.

This device is supported by the common qcom_defconfig

The DTB is called “qcs404-evb-4000.dtb”

Building steps

Steps:

  • Build u-boot

As above:

./tools/buildman/buildman -o .output qcom

Or for db410c (and other boards not supported by the generic target):

make CROSS_COMPILE=aarch64-linux-gnu- O=.output dragonboard410c_defconfig
make O=.output -j$(nproc)

  • gzip u-boot:

    gzip u-boot-nodtb.bin

  • Append dtb to gzipped u-boot:

    cat u-boot-nodtb.bin.gz arch/arm/dts/your-board.dtb > u-boot-nodtb.bin.gz-dtb

  • If you chose to build a FIT image, A qcom.its file can be found in board/qualcomm/generic/ directory. It expects a folder as qcom_imgs/ in the main directory containing pre-built kernel, dts and ramdisk images. See qcom.its for full path to images:

    mkimage -f qcom.its qcom.itb

  • Now we’ve got everything to build android boot image:

    mkbootimg --kernel u-boot-nodtb.bin.gz-dtb --ramdisk db845c.itb \
--output boot.img --pagesize 4096 --base 0x80000000

Or with no FIT image:

mkbootimg --kernel u-boot-nodtb.bin.gz-dtb \
--output boot.img --pagesize 4096 --base 0x80000000

  • Flash boot.img using fastboot and erase dtbo to avoid conflicts with our DTB:

    fastboot flash boot boot.img
fastboot erase dtbo