Custom BootLoader jump to FreeRTOS application

[pfifre]

Posted on May 19, 2014 at 10:23

Hi all,

I've develop a specific bootloader which calling my application.

My application is based on FreeRTOS.

When the application starts after the jump, the firmware crashes in hardfault.

It works fine when I don't use the FreeRTOS scheduler.

I've tested my application (with FreeRTOS enabled) by loading it with the debugger and it works fine.

FreeRTOS starts their tasks by calling SVC.

Then, i've try also to replace the FreeRTOS scheduler starting by a simply __asm volatile (''svc 0'') and I reproduce the same issue.

The application address is 0x0800C000.

Like clive suggested, I have use a system call in my bootloader :

void SVC_Handler(void)

{

pFunction  Jump_To_Application;

uint32_t  JumpAddress;

/* Jump to user application */

JumpAddress = *(__IO uint32_t*) (APPLICATION_ADDRESS + 4);

Jump_To_Application = (pFunction) JumpAddress;

__disable_irq();

/* Initialize user application's Stack Pointer */

__set_MSP(*(__IO uint32_t*) APPLICATION_ADDRESS);

Jump_To_Application();

}

I've checked the VECT_TAB_OFFSET in system_stm32f4xx.c to set it to 0xC000.

Can anybody help me ?

Thanks a lot,

Pascal

#stm32-freertos

[Tesla DeLorean]

Posted on May 19, 2014 at 17:06

What does it mean ?

I don't know, do you have linkage via the vector table? Does your Hard Fault handler output any diagnostic information? What debugger are you using?My example didn't disable interrupts, the expectation at the hand-over is that you've cleaned up the operating environment, and that the application can handle whatever is left.

Other Thread

https://community.st.com/0D50X00009XkiGuSAJ

 

EDIT: Fixed DEAD LINK, Original from 14-May-2014

[chen]

Posted on May 19, 2014 at 17:28

Hi

Reading the thread from top to bottom - I think you are confused as to what is doing what.

''I've develop a specific bootloader which calling my application.

My application is based on FreeRTOS.''

It is unclear now whether the bootloader is running FreeRTOS.

Does the bootloader run with FreeRTOS?

If so - why?

The bootloader only needs to :

download application code binary via USB

Program code into Flash.

Check if valid application code is in Flash

If Application code is valid - start it.

There is no need for the bootloader to run FreeRTOS - it only complicates the bootloader.

If the bootloader does not run FreeRTOS - the jump does not need to be in the SVC - simplifying your problem.

[pfifre]

Posted on May 19, 2014 at 17:43

How can I see if I have the linkage with the vector table?

I can read memory or the registers via the debugger.

I'm using GDB under Eclipse IDE.

Yes, I think your're right, the processor call the HardFault Handler because it didn't find any handler for SVC.

But, I'm sure that the VTOR points on 0x800C000.

''the expectation at the hand-over is that you've cleaned up the operating environment''

But the systemInit and main initialisation has been called before launch SVC.

Thanks for your help.

Pascal

[pfifre]

Posted on May 19, 2014 at 17:52

No, my bootloader doesn't run with FreeRTOS, but, my application does.

OK, I try a call from bootloader without SVC.

But, I do that before and I have the same problem.

Best regards,

Pascal

[Tesla DeLorean]

Posted on May 19, 2014 at 17:59

But, I'm sure that the VTOR points on 0x800C000.

If you are in the boot loader, then SCB->VTOR should point at THAT, the application should fix up it's vector address in SystemInit()

You are attempting to start an application image at 0x0800C000 from a boot loader at 0x08000000, right?

''the expectation at the hand-over is that you've cleaned up the operating environment''

 

But the systemInit and main initialization has been called before launch SVC.

Ok, but my point is that you shouldn't be leaving the kitchen messy, ie no random SysTick or TIM IRQ firing, and no DMA mid transaction.

[chen]

Posted on May 19, 2014 at 18:03

''No, my bootloader doesn't run with FreeRTOS, but, my application does.

OK, I try a call from bootloader without SVC''

You will definitely get a HardFault if you try to execute a SVC before the software has set up the ARM core with an ISR for the SVC.

If the bootloader is not running FreeRTOS - it should not be doing anything with SVC (unless it has set up a context switching system - again why would a simple bootloader do this?)

The application (with FreeRTOS) should set up the ARM core with context switching. The bootloader MUST not do anything that interfers with FreeRTOS.

One point which I tripped over - my bootloader does use the SysTick - the application MUST disable the SysTick as soon as possible, so that FreeRTOS can re-configure the SysTick for it's own use.

[pfifre]

Posted on May 20, 2014 at 08:57

Clive,

You are attempting to start an application image at 0x0800C000 from a boot loader at 0x08000000, right?

Yes, that's right.

And the SystemInit in BootLoader fixes up the VTOR to 0x8000000 and the Application fixes up to 0x800C000 in SystemInit to.

Ok, but my point is that you shouldn't be leaving the kitchen messy, ie no random SysTick or TIM IRQ firing, and no DMA mid transaction.

How can avoid these? Disable irq is not sufficient?

Thanks,

Pascal

[pfifre]

Posted on May 20, 2014 at 09:01

sung.chen_chung,

OK, I definitivly don't use the SVC in my bootloader.

The application MUST disable the SysTick as soon as possible

 

OK, I will try it.

Thanks for your support,

Pascal

[pfifre]

Posted on May 20, 2014 at 10:52

I've disabled SysTick at starting in my application.

Nothing change, I still have the same issue.

I simplify my application to not use FreeRTOS but simply call SVC at the beginning (__asm volatile(''svc 0'')).

The HardFault Handler is called immediatly.

It looks like that no handler will be load for treating SVC interrupt.

How can I verify that the vector table is loaded?

Best regards,

Pascal

[chen]

Posted on May 20, 2014 at 11:15

''I simplify my application to not use FreeRTOS but simply call SVC at the beginning (__asm volatile(''svc 0'')).''

Why are you doing this?

The 'SVC' is the ISR that handles context (task) switches in FreeRTOS. Without setting up tasks, there is not point calling the SVC

''SVCall - A supervisor call (SVC) is an exception that is triggered by the SVC

instruction. In an OS environment, applications can use SVC instructions to

access OS kernel functions and device drivers.''

''The HardFault Handler is called immediatly.''

This is expected - unless the SVC ISR has been set correctly - it will cause a hardfault.

''It looks like that no handler will be load for treating SVC interrupt.''

That is correct in this circumstance.

''How can I verify that the vector table is loaded?''

Not sure why you are asking this. I think you do not understand what is happening.

The Vector table should contain the 'default' ISR to call when there is an Interrupt.

Some IRQs may be disabled (but still have a valid entry in the vector table).

I do not understand what you are trying to do?

Have you managed to start the application from the bootloader?

Why are you changing the code in the application?

''I've disabled SysTick at starting in my application.

Nothing change, I still have the same issue.''

So you are getting a HardFault when starting the application.

Debug it.