I am working on an STM32f767 project with LWIP and MQTT. Everything seemed to work for a while but eventually, I received the following assert: "pbuf_free: p->ref > 0..." which caused it to crash sometimes; but sometimes it will continue to work without any issue. Has anyone had a similar issue?
According to LWIP_IAP example, memory location 0x20048000 is labeled as ethernet rx buffer location; however, I could not find where this location is linked to the ethernet rx buffer. for example, 0x2007C000 memory location in the linker file for RxDescripSection & TxDecripSection. And does the size of the MPU region have to be equal to or greater than MEM_SIZE defined in opt.h?
My settings:
LinkerScript.ld
Memory_B1(xrw) : ORIGIN = 0x2004C000, LENGTH = 0xA0
Memory_B2(xrw) : ORIGIN = 0x2004C0A0, LENGTH = 0xA0
.RxDecripSection (NOLOAD) : { *(.RxDescripSection) } >Memory_B1
.TxDecripSection (NOLOAD) : { *(.DMATxDscrTab_section) } >Memory_B2
.ARM.attributes 0 : { *(.ARM.attributes) }
main.c
/* Configure the MPU as Normal Non Cacheable for Ethernet Buffers in the SRAM2 */
MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.BaseAddress = 0x20048000;
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_NOT_CACHEABLE;
MPU_InitStruct.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER1;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL1;
MPU_InitStruct.SubRegionDisable = 0x00;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;
HAL_MPU_ConfigRegion(&MPU_InitStruct);
/* Configure the MPU as Device for Ethernet Descriptors in the SRAM2 */
MPU_InitStruct.Enable = MPU_REGION_ENABLE;
MPU_InitStruct.BaseAddress = 0x2004C000;
MPU_InitStruct.Size = MPU_REGION_SIZE_1KB;
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_SHAREABLE;
MPU_InitStruct.Number = MPU_REGION_NUMBER2;
MPU_InitStruct.TypeExtField = MPU_TEX_LEVEL0;
MPU_InitStruct.SubRegionDisable = 0x00;
MPU_InitStruct.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE
HAL_MPU_ConfigRegion(&MPU_InitStruct);
