[STM32F72x] Incorrect memory map

[Fabien-B]

I tried debugging an STM32F722 with blackmagic probe, and it worked... until my code grew bigger.
I looked into the code, the memory region for both flash and RAM are incorrect.

How to reproduce

• Place a breakpoint in a code located after 0x210000 (flash on ITCM interface)
• set mem inaccessible-by-default off
• Run code: the code does not stop at the breakpoint

Solution

RAM

It had no effect in my situation, but I replaced these two lines:

blackmagic/src/target/stm32f4.c

Lines 425 to 426 in 729b773

	target_add_ram32(target, 0x20000000, 0x20000); /* 128kiB DTCM RAM */
	target_add_ram32(target, 0x20020000, 0x60000); /* 384kiB RAM */

with

target_add_ram32(target, 0x20000000, 0x10000); /* 64kiB DTCM RAM */
target_add_ram32(target, 0x20010000, 0x30000); /* 192kiB RAM */

Flash

And I made it work by replacing these 2 lines:

blackmagic/src/target/stm32f4.c

Lines 477 to 478 in 729b773

	if (is_f7)
	stm32f4_add_flash(target, ITCM_BASE, 0x10000, 0x4000, 0, split);

with

if (is_f7) {
    stm32f4_add_flash(target, ITCM_BASE, 0x10000, 0x4000, 0, split);
    stm32f4_add_flash(target, ITCM_BASE+0x10000, 0x10000, 0x10000, 4, split);
    stm32f4_add_flash(target, ITCM_BASE+0x20000, 0x60000, 0x20000, 5, split);
}

Which is exactly the code a few lines below, except the STM32F72xxx is not dual bank.

blackmagic/src/target/stm32f4.c

Lines 486 to 492 in 729b773

	if (use_dual_bank) {
	if (is_f7) {
	const uint32_t bank1_base = ITCM_BASE + bank_length;
	stm32f4_add_flash(target, bank1_base, 0x10000, 0x4000, 0, split);
	stm32f4_add_flash(target, bank1_base + 0x10000U, 0x10000, 0x10000, 4, split);
	stm32f4_add_flash(target, bank1_base + 0x20000U, remaining_bank_length, 0x20000, 5, split);
	}

Next steps

I am not confident in doing a pull request because of the intricate code paths.
If I had to do it, I would probably try to replace all the if... else... by an array of structures defining the memory map for each devices. I am not sure that this is the path you want to take, and maybe there are issues with this method I don't foresee, so I am leaving it to you to decide what to do.