Note: To see the exact sequence of steps in which applications and secondary bootloader (SBL) are converted from compiler generated .out files to boot images, see the makefile makefile_ccs_bootimage_gen that is included in every example and secondary bootloader (SBL) CCS project.; If you are using makefile based build, then see the file named makefile in the example folder.

Introduction

This section describes the various tools that are used to create boot images for all the SDK applications

Important files and folders

Folder/Files	Description
${SDK_INSTALL_PATH}/tools/boot/
multicoreImageGen/	Tool to combine multiple RPRC into a single binary
out2rprc/	Tool to convert compiler generated ELF .out for a CPU to a compact and loadable binary representation, called RPRC.
sbl_prebuilt/	Pre-built secondary bootloader (SBL) images and flash configuration files for different supported EVMs, see also Flashing Tools
signing/	Security signing scripts need to create boot images that can be booted by ROM bootloader (RBL)
xipGen/	Tool to split a RPRC file generated from `out2rprc` into two files containing non-XIP and XIP sections.
uart_bootloader.py	Python script used to send the SBL and appimage binaries over UART using XMODEM protocol in UART boot mode
uart_uniflash.py	Python script used to flash SBL and applications to EVM flash using UART. See Flashing Tools for more details.
genimage.py	Python script used to generate multicore elf image from individual core elf images.

MCELF Image Gen

This tool takes individual core ELF files as input and combines their segments to create a single ELF file.
Shown below is the file format for an mcelf image file and its metacontent as seen by readelf

MCELF Image File Format

Segment data from each input ELF file is extracted and appended together to form a single list of segments.
The program header table fields are then re-calculated and the header table is regenerated using information from this new segment list.
Once that is done, from the updated program header, the ELF header is regenerated.
The first segment is the note segment. It can be customized to store information according to your application. By default the note segment contains vendor information, segment to core mapping and entry points.
The segment sizes can be manipulated using appropriate arguments.

Argument	Description
`--core-img`	Path to individual binaries of each core. It is a mandatory argument. Input is given in this format: `--core-img=0:<core0_binary.out> --core-img=1:<core1_binary.out>`
`--output`	The output file name. It is a mandatory argument. `--output=<file_name>.mcelf`
`--merge-segments`	Enable merging segments based on a tolerance limit. Default value is false.
`--tolerance-limit`	The maximum difference (in bytes) between the end address of previous segment and start address of current segment for merging the segments. Default value is zero.
`--ignore-context`	Enable merging of segments that are of different cores. Default value is false.
`--xip`	XIP section's start and end address seperated by a colon. It creates a new file `<filename>.mcelf_xip`. Default value is 'none' (XIP is disabled). To enable XIP creation: `--xip=0x60100000:0x60200000`
`--max_segment_size`	Maximum allowed size of a loadable segment. This feature can only be used with merge_segments disabled. Default value is 8192 bytes.
`--xlat`	SOC specific Address Translation. (Under development, reserved for future use)
`--sso`	Shared static objects. (Under development, reserved for future use)

The input for arguments 3-7 are defined in {MCU_SDK_PATH}/devconfig/devconfig.mak file.
Given below are the structs used in the bootloader library to parse a 32 bit MCELF binary

#define E_IDENT 16
 
/* ELF HEADER */
typedef struct Bootloader_ELFH32_s
{
    uint8_t  e_ident[E_IDENT];
    uint16_t e_type;
    uint16_t e_machine;
    uint32_t e_version;
    uint32_t e_entry;
    uint32_t e_phoff;
    uint32_t e_shoff;
    uint32_t e_flags;
    uint16_t e_ehsize;
    uint16_t e_phentsize;
    uint16_t e_phnum;
    uint16_t e_shentsize;
    uint16_t e_shnum;
    uint16_t e_shstrndx;
 
} Bootloader_ELFH32;
 
/* PROGRAM HEADER */
typedef struct Bootloader_ELFPH32_s
{
    uint32_t type;
    uint32_t offset;
    uint32_t vaddr;
    uint32_t paddr;
    uint32_t filesz;
    uint32_t memsz;
    uint32_t flags;
    uint32_t align;
 
} Bootloader_ELFPH32;
 
/* NOTE SEGMENT */
typedef struct Bootloader_ELFNote_s
{
    uint32_t namesz;
    uint32_t descsz;
    uint32_t type;
} Bootloader_ELFNote;

Use the following command to invoke this script to generate a basic .mcelf image from input .out files without any segment manipulations

$ cd tools/boot/multicoreELFImageGen
 
$ {PYTHON} genimage.py --core-img={CORE_0_ID}:{core0_app.out} --core-img={CORE_1_ID}:{core1_app.out} --core-img={CORE_2_ID}:{core2_app.out} --core-img={CORE_3_ID}:{core3_app.out} --output={application.mcelf}

The various core ID to be used are as below.

CORE	CORE ID
wkup-r5fss0-0	0
r5fss0-0	1
r5fss0-1	2
r5fss1-0	3
r5fss1-1	4
c75ss0-0	5
c75ss1-0	6

Signing Scripts

To run these scripts, one needs openssl installed as mentioned here, OpenSSL
Signing scripts are a collection of scripts needed to sign ROM images (image booted by ROM - mostly the SBL) and application images (image booted by the SBL)
The RBL requires the boot image (mostly SBL), to be signed always, even if we are not using secure boot.
We follow a combined boot method for ROM images. Here the ROM Bootloader (RBL) boots the SBL, SYSFW and BOARDCFG together. The boot image would be a binary concatenation of x509 Certificate, SBL, SYSFW, BOARDCFG (and the SYSFW inner certificate in case of HS device) binary blobs. We use a python script to generate this final boot image. This script has a dependency on openssl as mentioned before, so make sure you've installed it. To generate a combined boot image, one can do as below:
For GP devices
cd ${SDK_INSTALL_PATH}/tools/boot/signing

${PYTHON} rom_image_gen.py --swrv 1 --sbl-bin <path-to-sbl-binary> --sysfw-bin <path-to-sysfw-binary> --boardcfg-blob <path-to-boardcfg-binary-blob> --boardcfg-sbldata-blob <path-to-boardcfg-sbldata-blob> --sbl-loadaddr ${SBL_RUN_ADDRESS} --sysfw-loadaddr ${SYSFW_LOAD_ADDR} --bcfg-loadaddr ${BOARDCFG_LOAD_ADDR} --bcfg-sbldata-loadaddr ${BOARDCFG_SBLDATA_LOAD_ADDR} --key ${BOOTIMAGE_CERT_KEY} --rom-image <path-to-output-image> --enable-sbldata yes
For HS devices, we have to pass the HS SYSFW binaries and also the SYSFW inner certificate to the signing script.
cd ${SDK_INSTALL_PATH}/tools/boot/signing

${PYTHON} rom_image_gen.py --swrv 1 --sbl-bin <path-to-sbl-binary> --sysfw-bin <path-to-sysfw-binary> --sysfw-inner-cert <path-to-sysfw-inner-cert-binary> --boardcfg-blob <path-to-boardcfg-binary-blob> --boardcfg-sbldata-blob <path-to-boardcfg-sbldata-blob> --sbl-loadaddr ${SBL_RUN_ADDRESS} --sysfw-loadaddr ${SYSFW_LOAD_ADDR} --bcfg-loadaddr ${BOARDCFG_LOAD_ADDR} --bcfg-sbldata-loadaddr ${BOARDCFG_SBLDATA_LOAD_ADDR} --key ${BOOTIMAGE_CERT_KEY} --rom-image <path-to-output-image> --enable-sbldata yes
For SBL images or examples which is loaded by SBL, we use a different signing script. This is solely because of the x509 certificate template differences between ROM and SYSFW. In GP devices appimages are not signed. The signing happens only in HS devices. The script usage is:
cd ${SDK_INSTALL_PATH}/tools/boot/signing

$(PYTHON) appimage_x509_cert_gen.py --bin <path-to-the-binary> --authtype 0 --loadaddr 84000000 --key <signing-key-derived-from-devconfig> --output <output-image-name> --keyversion 1.5
In the case of encryption, two extra options are also passed to the script like so:
cd ${SDK_INSTALL_PATH}/tools/boot/signing

$(PYTHON) appimage_x509_cert_gen.py --bin <path-to-the-binary> --authtype 0 --loadaddr 84000000 --key <signing-key-derived-from-devconfig> --enc y --enckey <encryption-key-derived-from-devconfig> --output <output-image-name> --keyversion 1.5
These scripts are invoked in makefiles, and the image generation happens automatically along with the example build. So mostly these scripts need not be manually run.
- Here,
  - SBL_RUN_ADDRESS is 0x43C00000
  - In the case of GP device, BOOTIMAGE_CERT_KEY is app_degenerateKey.pem
  - In the case of HS device, BOOTIMAGE_CERT_KEY is custMpk_am275x .pem.

These scripts are invoked in makefiles, and the image generation happens automatically along with the example build. So mostly these scripts need not be manually run. If the user build-system is different from TI's makefile system, it needs to be ensured that the same is followed as part of the post build steps. The devconfig has ENC_SBL_ENABLED=yes and that is why for HS-SE devices, the SBL image is encrypted by default.

UART Bootloader Python Script

This script is used in UART boot mode for sending the SBL and appimage binaries to the EVM via UART using XMODEM protocol
Make sure that python3 and its dependent modules are installed in the host machine as mentioned in Python3
Booting via UART is slow, but is useful if application loading via CCS or OSPI boot is not an option
Make sure the UART port used for terminal is identified as mentioned in Setup UART Terminal
Make sure you have the EVM power cable and UART cable connected as shown in Cable Connections
To boot applications using this script, POWER OFF the EVM
Switch to UART BOOT MODE.
POWER ON the EVM
To confirm that the board is in UART boot mode, open the UART terminal and confirm that you see the character 'C' getting printed on the console every 2-3 seconds.
Now close the terminal. This is important as the script won't be able to function properly if the UART terminal is open.
Update the appimage path on sbl_prebuilt/{board}/default_sbl_uart_hs_fs.cfg file

Note: For HS-SE device, use default_sbl_uart_hs.cfg as the cfg file.

Open a command prompt and run the below command to send the SBL and application binary to the EVM
- on Linux
  cd ${SDK_INSTALL_PATH}/tools/boot
  
  python uart_bootloader.py -p /dev/ttyUSB0 --cfg=sbl_prebuilt/{board}/default_sbl_uart_hs_fs.cfg
- on Windows
  cd ${SDK_INSTALL_PATH}/tools/boot
  
  python uart_bootloader.py -p -p COM<x> --cfg=sbl_prebuilt/{board}/default_sbl_uart_hs_fs.cfg
When you execute this, the script first sends the uart bootloader, and then the multicore appimage
After the multicore appimage is successfully parsed, the uart bootloader sends an acknowledgment to the script and waits for 5 seconds before running the application binary
Upon receiving the ack, the script will exit successfully
Connect to the UART terminal within 5 seconds to see logs from the application
Below are the logs of the script after all the files have been sent
Sending the UART bootloader sbl_prebuilt/{board}/sbl_uart.release.tiimage ...

Sent bootloader sbl_prebuilt/{board}/sbl_uart.release.tiimage of size 243975 bytes in 23.94s.

Sending the application ../../examples/drivers/udma/udma_memcpy_polling/{board}/r5fss0-0_nortos/ti-arm-clang/udma_memcpy_polling.release.appimage ...

Sent application ../../examples/drivers/udma/udma_memcpy_polling/{board}/r5fss0-0_nortos/ti-arm-clang/udma_memcpy_polling.release.appimage of size 99580 bytes in 11.74s.

[STATUS] Application load SUCCESS !!!

Connect to UART in 5 seconds to see logs from UART !!!

HSM Appimage Generator Tool

Note: Change DEVICE_TYPE to HS in ${SDK_INSTALL_PATH}/devconfig/devconfig.mak and then generate Linux Appimage for HS-SE device.

This tool generates a HSM Appimage by taking the HSM binaries (.bin file) as input and generates an appimage containing the input HSM binary.
The input file location can be mentioned in the config.mak file located at {SDK_INSTALL_PATH}/tools/boot/HSMAppimageGen/board/am275x-evm
The input file name for HSM bin file can be mentioned in the config.mak file.
- #Input binary name
  HSM_BINARY_NAME = HSM_min_sample.bin
The output appimage name can be mentioned in the config.mak file.
- #Output appimage name
  HSM_APPIMAGE_NAME=hsm.appimage

Run the makefile at {SDK_INSTALL_PATH}/tools/boot/HSMAppimageGen to generate the HSM appimage

For Windows

  cd ${SDK_INSTALL_PATH}/tools/boot/HSMAppimageGen
  gmake -s BOARD=am275x-evm all

For Linux

  cd ${SDK_INSTALL_PATH}/tools/boot/HSMAppimageGen
  make -s BOARD=am275x-evm all

The HSM appimage wil be generated at {SDK_INSTALL_PATH}/tools/boot/HSMAppimageGen/board/am275x-evm after running the makefile