Memory management is a very good start with a H7 and lwIP.
In a H723/H735 (I think that one has another memory layout than the H743) I created some extra sections:
linker file:
/* Specify the memory areas */
MEMORY
{
ITCMRAM (xrw): ORIGIN = 0x00000000, LENGTH = 64K
FLASH (rx): ORIGIN = 0x08000000, LENGTH = 1024K
/* DTCM: 128 kB
* 0x2000 0000 - 0x2001FFFF
* used as "general" RAM
* !!! no DMA access !!!
*/
DTCM_HPST(xrw) : ORIGIN = 0x20000000, LENGTH = 5K /* DTCM heap & stack */
DTCM_NOINIT(xrw) : ORIGIN = 0x20001400, LENGTH = 1K /* DTCM no init */
DTCMRAM(xrw) : ORIGIN = 0x20001800, LENGTH = 122K /* DTCM */
SRAXI_D1(xrw) : ORIGIN = 0x24000000, LENGTH = 128K
SRAXI_D1_LWIP(xrw) : ORIGIN = 0x24020000, LENGTH = 128K
SRAXI_D1_A2IP(xrw) : ORIGIN = 0x24040000, LENGTH = 64K
SRAM1_D2(xrw) : ORIGIN = 0x30000000, LENGTH = 16K
SRAM2_D2(xrw) : ORIGIN = 0x30004000, LENGTH = 16K
SRAM4_D3(xrw) : ORIGIN = 0x38000000, LENGTH = 16K /* only D3 access */
OSPI2_D1(xrw) : ORIGIN = 0x70000000, LENGTH = 0x1000000 /* OCTOSPI 2 */
}
...
/* +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ */
/* lwIP in SRAXI_D1 */
/* lwIP HEAP section */
.LwipHeapSection (NOLOAD):
{
. = ALIGN(4);
*(.LwipHeapSection)
*(.LwipHeapSection*)
. = ALIGN(4);
} >SRAXI_D1_LWIP
/* lwIP POOL section */
.LwipPoolSection (NOLOAD):
{
. = ALIGN(4);
*(.LwipPoolSection)
*(.LwipPoolSection*)
. = ALIGN(4);
} >SRAXI_D1_LWIP
then in lwIP's arch.h I placed RX pool and lwIP heap in these AXI SRAM areas:
/** Allocates a memory buffer of specified size that is of sufficient size to align
* its start address using LWIP_MEM_ALIGN.
* You can declare your own version here e.g. to enforce alignment without adding
* trailing padding bytes (see LWIP_MEM_ALIGN_BUFFER) or your own section placement
* requirements.\n
* e.g. if you use gcc and need 32 bit alignment:\n
* \#define LWIP_DECLARE_MEMORY_ALIGNED(variable_name, size) u8_t variable_name[size] \_\_attribute\_\_((aligned(4)))\n
* or more portable:\n
* \#define LWIP_DECLARE_MEMORY_ALIGNED(variable_name, size) u32_t variable_name[(size + sizeof(u32_t) - 1) / sizeof(u32_t)]
*/
#ifndef LWIP_DECLARE_MEMORY_ALIGNED
#define LWIP_DECLARE_MEMORY_ALIGNED(variable_name, size) u8_t variable_name[LWIP_MEM_ALIGN_BUFFER(size)] __attribute__((section(".LwipPoolSection")))
#endif
#ifndef LWIP_DECLARE_MEMORY_ALIGNED_HEAP
#define LWIP_DECLARE_MEMORY_ALIGNED_HEAP(variable_name, size) u8_t variable_name[LWIP_MEM_ALIGN_BUFFER(size)] __attribute__((section(".LwipHeapSection")))
#endif
