porting to qspi flash based - hardfault on unalinged access

[RobertW]

Dear All

I got the job to port a existing app which was developed for stm32h743 with 2mb flash to a stm32h750 with 128kb flash and a 8MB qspi memory.

I basically succeeded in having a ext boot rom scenario where i would start from flash , enable qspi and memory map it. Then i point to it and jump. I ve found a working external loader so i can run the final app via that from the IDE ( load it and debug).

Now the app crashes mostly with unaligned accesses either in the touchgfx init or lwip or mbedtls software.

My research leads me to either a dma issue or wrong mpu settings sofar. What would be a general things to do when doing such a port ? Beside setting up qspi into memory mapped mode, changing the .ld file to point to my qspi flash (0x9000000) etc .. are there any other steps i need to consider here ?

[RobertW]

HAL_MPU_Disable();

/* Configure the MPU attributes as WT for SRAM */
MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.BaseAddress = 0x30000000;
MPU_InitStruct.Size = MPU_REGION_SIZE_256KB;
MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
MPU_InitStruct.IsShareable = MPU_ACCESS_SHAREABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER0;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
MPU_InitStruct.SubRegionDisable = 0x00;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_DISABLE;
HAL_MPU_ConfigRegion(&MPU_InitStruct);

/* Configure the MPU attributes as Device not cacheable for ETH DMA descriptors */
MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.BaseAddress = 0x30040000;
MPU_InitStruct.Size = MPU_REGION_SIZE_256B;
MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
MPU_InitStruct.IsBufferable = MPU_ACCESS_BUFFERABLE;
MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER1;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;
MPU_InitStruct.SubRegionDisable = 0x00;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;
HAL_MPU_ConfigRegion(&MPU_InitStruct);

/* Configure the MPU attributes as Cacheable write through
for LwIP RAM heap which contains the Tx buffers */
MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.BaseAddress = 0x30044000;
MPU_InitStruct.Size = MPU_REGION_SIZE_16KB;
MPU_InitStruct.AccessPermission = MPU_REGION_FULL_ACCESS;
MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
MPU_InitStruct.IsCacheable = MPU_ACCESS_CACHEABLE;
MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER2;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;
MPU_InitStruct.SubRegionDisable = 0x00;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;

MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER3;
MPU_InitStruct.BaseAddress = 0x90000000;
MPU_InitStruct.Size = MPU_REGION_SIZE_256MB;
MPU_InitStruct.SubRegionDisable = 0x0;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
MPU_InitStruct.AccessPermission = MPU_REGION_NO_ACCESS;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_DISABLE;
MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;
MPU_InitStruct.IsBufferable = MPU_ACCESS_NOT_BUFFERABLE;
HAL_MPU_ConfigRegion(&MPU_InitStruct);

MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER4;
MPU_InitStruct.BaseAddress = 0x90000000;
MPU_InitStruct.Size = MPU_REGION_SIZE_8MB;
MPU_InitStruct.SubRegionDisable = 0x0;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
MPU_InitStruct.AccessPermission = MPU_REGION_PRIV_RO;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;
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);

[Pavel A.]

> Now the app crashes mostly with unaligned accesses 

Unaligned accesses on what? data (where?) or instructions?

[FBL]

Hello @RobertW,

Could you please share a screenshot of the exception viewer to inspect the fault when it occurs, 
It is possible that MPU crash due to write issued to flash region or due to executing data as code... Make sure to configure the indirect mode before switching to memory mapped mode.

Hope this helps!