QNX)¶

11.3.1. Introduction¶

There are two bootloaders in Processor SDK J721S2 (RTOS/Linux/QNX). They are:

RTOS SDK Bootloader

Linux SDK Bootloader

This developer note describes about these two bootloaders.

11.3.2. RTOS SDK Bootloader¶

RTOS Bootloader is referred to as SBL (Secondary bootloader).

This is included in Processor SDK RTOS at

pdk_<device>_<version>/packages/ti/boot

This is used when all cores on the SoC run FreeRTOS. Following are the details regarding boot files in the SD card:

tiboot3.bin - this is the SBL which the ROM bootloader will boot on MCU R5F Core0
tiboot3.bin will boot tifs.bin - this is the DMSC firmware binary
tiboot3.bin will boot a file called “app”.

If “app” is “combined boot image”, it contains binaries of all other CPUs like A72, Main R5F, C7x. “combined boot image” is created by running an offline tool which covert elf .out files to .rprc format and then combines these to something called “multi-core image”

If “app” is “BootAPP”, please refer below table.

See also

See PDK’s bootloader page for more info on this .rprc file and offline boot tools

The table below provides more information about the features and differences between the SBL bootloader and the “Boot App”:

Feature area	SBL Description	“Boot App”	Key Diffs / Comments
Initial Bootloader	YES	NO	Boot app is a “tertiary” bootloader
SoC’s Supported	J7200/J721E/J721S2/J784S4/J722S	J7200/J721E/J721S2/J784S4
Device types supported	GP, HS	GP, HS	NOTE: most, but not all, features are supported for each device type. Check specific feature support listed in each release.
Runs on MCU R5F	YES	YES	NOTE: the SBL is used to boot the Boot App
Can support startup with MCU domain only	YES	YES
Boot media supported	UART, MMCSD, OSPI	MMCSD, OSPI	UART boot supported with SBL only
Supports booting HLOS + RTOS images	YES	YES	SBL uses “combined appimage” build to put all RTOS & HLOS images into a single .appimage, whereas a specific format of combined images is used with the boot app.
Boots another app to MCU R5F	YES		Boot app doesn’t support booting an app to the MCU R5F (since it is the app already running on that processor)
Image Layout	single appimage	3-5 different appimages	SBL: all images for the remote cores to be booted must all be combined in to a single .appimage file that is either placed on the SD card (for MMCSD boot) or is flashed to a single flash addr location (for xSPI / OSPI boot). This includes all HLOS & RTOS images that must be booted. “Boot App”: images for remote cores to be booted are split up into 3-5 different appimage files for either SD card booting or flashed into 3-5 different flash addresses for xSPI / OSPI booting (see details in the MCUSW CAN Boot App documentation).

11.3.3. Linux SDK Bootloader¶

TI Linux SDK utilizes ti-u-boot as a bootloader option for our SoCs which is available at (https://git.ti.com/cgit/ti-u-boot/ti-u-boot/) and also included in Processor SDK Linux at below path

board-support/u-boot-<version and git tag>

In addition to qnx-ifs, the following files are loaded to the boot partition of the SD card when using this boot method.

tiboot3.bin contains the R5 U-Boot SPL, TIFS (system firmware), and the cut down device tree for the R5 u-boot SPL. This is what public ROM code will load to SRAM and run on MCU/WKUP domain R5_core0.
tispl.bin contains DM firmware and the following components for the Coretex-A cores:
- Arm Trusted Firmware
- OPTEE (empty if not used)
- U-Boot SPL
- Device Tree for Cortex-A U-Boot SPL
u-boot.img is started by the U-Boot SPL.
Any variables set in the uEnv.txt file will override U-Boot defaults. The run envboot command (which runs automatically if U-Boot prompt is not interrupted) will perform the tasks inside the uenvcmd variable. This is typically to load any remote core binaries (like R5F, C7x), test conditions, and run U-Boot commands. The last thing uenvcmd calls for is to load qnx-ifs (and dtb depending on QNX SDP version) to DDR and start QNX.
If using QNX SDP version 8.0+ (used by Processor SDK QNX 10.0+), a device tree file (.dtb) will be present and required by QNX as well.

Hint

U-Boot knows where to find remote core binaries in <rootfs>/lib/firmware. If using eMMC as boot media, remote core binaries will be in a different location as specified by How To Use EMMC Based Filesystem and our uEnv.txt file helps U-Boot find the correct eMMC partition

Warning

U-Boot does not always take QNX into consideration when making design decisions. New versions of U-Boot may change things QNX relies on and while we test our SDK releases for proper behavior, future or past versions of U-Boot may require patching to either U-Boot or QNX.