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

We will build u-boot-nodtb.bin from the u-boot source tree.

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

Use the following commands:

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

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

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

Or for smartphones:

make CROSS_COMPILE=aarch64-linux-gnu- O=.output qcom_defconfig qcom-phone.config
make CROSS_COMPILE=aarch64-linux-gnu- 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

Other devices with boot image version 2 can be built like this example:

mkbootimg --pagesize 4096 --header_version 2 \
--kernel_offset 0x00008000 --kernel u-boot-nodtb.bin.gz \
--dtb_offset 0x01f00000 --dtb dts/upstream/src/arm64/qcom/qcm6490-fairphone-fp5.dtb \
--output boot.img

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