Integrating wolfBoot into PlatformIO

samsonw · February 22, 2023, 1:53pm

Hi all,

I was trying to add wolfboot library ( which uses as a secure bootloader and for OTA firmware upgrades written in C) to my project which is based on Arduino platform , and then I got the following error ,

I used C calling syntax for all the header files in wolfboot library which is ,

#ifdef __cplusplus
 extern "C" {
#endif

After all function declarations, add:

#ifdef __cplusplus
}
#endif

Still the same error ,appreciate if anyone has a clue on why this compile error pops up .

my .ini is
[env:nucleo_f767zi]
platform = ststm32
board = nucleo_f767zi
framework = arduino

Thanks.

maxgerhardt · February 22, 2023, 2:03pm

The library wants you to implement hal_flash_write(). In which file did you create that function?

maxgerhardt · February 22, 2023, 2:14pm

Well actually no. The WolfSSL library should provide these functions when they’re properly compiled in. See

github.com

wolfSSL/wolfBoot/blob/master/hal/stm32f7.c

/* stm32f7.c
 *
 * Copyright (C) 2021 wolfSSL Inc.
 *
 * This file is part of wolfBoot.
 *
 * wolfBoot is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * wolfBoot is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
 */

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and it will also want you to use this linker file

github.com

wolfSSL/wolfBoot/blob/master/hal/stm32f7.ld

MEMORY
{
    FLASH (rx) : ORIGIN = 0x08000000, LENGTH = @BOOTLOADER_PARTITION_SIZE@
    RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 0x00020000 /* mapping TCM only */
}

SECTIONS
{
    .text :
    {
        _start_text = .;
        KEEP(*(.isr_vector))
        *(.text*)
        *(.rodata*)
        . = ALIGN(4);
        _end_text = .;
    } > FLASH

    .edidx :
    {

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Which then ends up conflicting with Arduino though, so you’ll have to reconcile both parts.

samsonw · February 22, 2023, 2:17pm

Yes it is provided by wolfssl library . So do i need to add those linker files to a specific location ?

maxgerhardt · February 22, 2023, 2:23pm

You should solve the undefined reference error first. Do you see that stm32f7.c file going into the build? Does it exist in your project?

samsonw · February 22, 2023, 2:29pm

No it doesn’t .I deleted that folder which comes in with the wolfboot assuming that the those hal functions will use stm32f7.c from arduinio stm core. May be i should add those file back and compile .

samsonw · February 22, 2023, 2:39pm

I just copied stm32f7.c file from hal folder which provided by the wolfssl to the src directory and compiled, now there’s no more compile error.
Should I also need to update the linker file which provided by them with the stm arduino core linker file ?

samsonw · February 22, 2023, 3:14pm

Look like everything fine now ,thanks @maxgerhardt !

maxgerhardt · February 22, 2023, 4:30pm

Actually, are you sure? I took one more look at it and it looks to me like there should be two binaries involved. Once, you build + upload the bootloader (“wolfBoot.bin”) from the repo. The bootloader is only linked with that special linker file, it restricts it to the start at the start of flash ( 0x08000000) and the value of BOOTLOADER_PARTITION_SIZE. Only source codes from wolfBoot go into the wolfBoot.bin, none of your firmware or the Arduino stuff.

Then you have to adapt your (Arduino) firmware to start at a different offset, aka after the bootloader, which is when I read this correctly is 0x08020000. However, there is a 0x100 big firmware image header before the actual entry point that is generated “somehow”.

With this, the Arduino linker script should be unmodified, but you still have to tell it the offset (doable via this) and probably do a special post-processing step to correctly append the header.

samsonw · February 22, 2023, 6:04pm

Correct ,that I modified the existing linker script when building the my build+the bootloader for the give start address by the wolfboot .That I have done in a separate task. Currently i’m working on with the OTA update process and try to add the wolfboot library to the firmware and use their API’s.