HardFault on touchgfx::Application::drawCachedAreas()

[I_ve_got_a_problem]

Hi!

I have a board with a STM32H730 chip, my RAM is configured as not cacheable and instruction access disabled,as performance decreases a lot otherwise, but now i'm getting a hardfault after drawCachedAreas(); is executed,

As i can't see what that function is doing, i thought that mayb someone could help me. 

If someone is invested enough here is my MPU config

void MPU_Config(void)
{
    MPU_Region_InitTypeDef MPU_InitStruct;

    /* 1) Deshabilita el MPU para reconfigurar */
    HAL_MPU_Disable();

    /* ————————————————————————————————————————————————————
     * Región 0: fondo 4 GB NO_ACCESS (cubre todo excepto QSPI, SDRAM y SRAM)
     *———————————————————————————————————————————————————*/
    MPU_InitStruct = (MPU_Region_InitTypeDef){0};
    MPU_InitStruct.Enable           = MPU_REGION_ENABLE;
    MPU_InitStruct.Number           = MPU_REGION_NUMBER0;
    MPU_InitStruct.BaseAddress      = 0x00000000U;
    MPU_InitStruct.Size             = MPU_REGION_SIZE_4GB;
    MPU_InitStruct.SubRegionDisable = 0x87;                    // deja libres subregs 2 y 3
    MPU_InitStruct.TypeExtField     = MPU_TEX_LEVEL0;
    MPU_InitStruct.AccessPermission = MPU_REGION_NO_ACCESS;
    MPU_InitStruct.DisableExec      = MPU_INSTRUCTION_ACCESS_DISABLE;
    MPU_InitStruct.IsShareable      = MPU_ACCESS_SHAREABLE;
    MPU_InitStruct.IsCacheable      = MPU_ACCESS_NOT_CACHEABLE;
    MPU_InitStruct.IsBufferable     = MPU_ACCESS_NOT_BUFFERABLE;
    HAL_MPU_ConfigRegion(&MPU_InitStruct);

    /* ————————————————————————————————————————————————————
     * Región 1: QSPI externa @0x9000_0000, 64 MB (XIP)
     *———————————————————————————————————————————————————*/
    MPU_InitStruct = (MPU_Region_InitTypeDef){0};
    MPU_InitStruct.Enable           = MPU_REGION_ENABLE;
    MPU_InitStruct.Number           = MPU_REGION_NUMBER1;
    MPU_InitStruct.BaseAddress      = 0x90000000U;
    MPU_InitStruct.Size             = MPU_REGION_SIZE_64MB;
    MPU_InitStruct.SubRegionDisable = 0x0;
    MPU_InitStruct.TypeExtField     = MPU_TEX_LEVEL1;          // normal, cacheable
    MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
    MPU_InitStruct.DisableExec      = MPU_INSTRUCTION_ACCESS_ENABLE; // XIP
    MPU_InitStruct.IsShareable      = MPU_ACCESS_NOT_SHAREABLE;
    MPU_InitStruct.IsCacheable      = MPU_ACCESS_CACHEABLE;
    MPU_InitStruct.IsBufferable     = MPU_ACCESS_BUFFERABLE;
    HAL_MPU_ConfigRegion(&MPU_InitStruct);

    /* ————————————————————————————————————————————————————
     * Región 2: SDRAM externa @0x7000_0000, 8 MB  <— toda la RAM externa
     *   • non-cacheable  (evita incoherencias LTDC/DMA)
     *   • non-bufferable (hace el bus más “estricto” pero es el estado original)
     *   • shareable       (mantiene coherencia para masters DMA)
     *———————————————————————————————————————————————————*/
    MPU_InitStruct = (MPU_Region_InitTypeDef){0};
    MPU_InitStruct.Enable           = MPU_REGION_ENABLE;
    MPU_InitStruct.Number           = MPU_REGION_NUMBER2;
    MPU_InitStruct.BaseAddress      = 0x70000000U;
    MPU_InitStruct.Size             = MPU_REGION_SIZE_8MB;
    MPU_InitStruct.SubRegionDisable = 0x0;
    MPU_InitStruct.TypeExtField     = MPU_TEX_LEVEL0;
    MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
    MPU_InitStruct.DisableExec      = MPU_INSTRUCTION_ACCESS_DISABLE;
    MPU_InitStruct.IsShareable      = MPU_ACCESS_SHAREABLE;
    MPU_InitStruct.IsCacheable      = MPU_ACCESS_NOT_CACHEABLE;   
    MPU_InitStruct.IsBufferable     = MPU_ACCESS_NOT_BUFFERABLE;  
    HAL_MPU_ConfigRegion(&MPU_InitStruct);

    /* ————————————————————————————————————————————————————
     * Región 3: AXI-SRAM interna @0x2400_0000, 512 KB
     *   • cacheable + bufferable para código/variables críticas
     *———————————————————————————————————————————————————*/
    MPU_InitStruct = (MPU_Region_InitTypeDef){0};
    MPU_InitStruct.Enable           = MPU_REGION_ENABLE;
    MPU_InitStruct.Number           = MPU_REGION_NUMBER3;
    MPU_InitStruct.BaseAddress      = 0x24000000U;
    MPU_InitStruct.Size             = MPU_REGION_SIZE_512KB;
    MPU_InitStruct.SubRegionDisable = 0x0;
    MPU_InitStruct.TypeExtField     = MPU_TEX_LEVEL0;
    MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
    MPU_InitStruct.DisableExec      = MPU_INSTRUCTION_ACCESS_ENABLE;
    MPU_InitStruct.IsShareable      = MPU_ACCESS_NOT_SHAREABLE;
    MPU_InitStruct.IsCacheable      = MPU_ACCESS_CACHEABLE;
    MPU_InitStruct.IsBufferable     = MPU_ACCESS_BUFFERABLE;
    HAL_MPU_ConfigRegion(&MPU_InitStruct);

    /* 2) Reactiva el MPU con “privileged default map” para todo lo que no cubran
       las regiones anteriores */
    HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);
}

Base addresses are all like in the linker file, except flash that starts at 0x90000200

**EDIT** 

I forgot to mention, in the MPU config if i set RAM as cacheable, the hardFault dissapears, but i need it to be not cacheable or i get like 10 times worse performance. 

[GaetanGodart]

Hello @I_ve_got_a_problem ,

I am no expert on cache but it says it is not aligned.

In the linker script, do you align your sections like we do :

Regards,

[I_ve_got_a_problem]

Yes!

I also suspected it was an alignment problem, but I have tried different alignments and none have worked, so I came back to the one the .ioc generates for touchgfx, 

What makes it hard to debug, is the fact that I have no clue of what Application::drawCachedAreas() does, since it is already compiled in the touchgfx library.

I know the problem isn't the function itself, but rather my MPU_Configuration, but i can't know where is faulting, so I lack a starting point.

The problem has been transfered to some colleagues now, and they are trying things, but we could appreciate if you could share some light into what the function does, beyond what the name tells us.

Thanks for the response anyways!

[GaetanGodart]

Hello @I_ve_got_a_problem ,

It is quite hard for me to help you on MPU configuration but perhaps I can share some resources that would be useful :

1. http://st.com/resource/en/application_note/an4838-introduction-to-memory-protection-unit-management-on-stm32-mcus-stmicroelectronics.pdf
2. https://support.touchgfx.com/docs/development/scenarios/running-graphics-on-stm32h7r

Please tell me if it is of any help!

Regards,