[feature] st-util with SWO support possible?

[mhanuel26]

• Stlink/v2-onboard
• Linux
• st-util
• STM32F769 Discovery

I was wondering if it's possible to have SWO output from target. It will be great to have sort of printf window for debug messages.
The closest minimalist solution I have found is explained here, but depends on STM32 ST-Link Utility or Keil uVision for it.

Please let me know your thoughts,

[xor-gate]

Its possible, but not implemented. OpenOCD has support for this to write ITM port 0 or 1 to a file.

[shizacat]

Hello,
Do you plan to implement swo?

[romansavrulin]

+1 on SWO feature

[langhaarschneider]

also +1 on SWO feature

[simplerobot]

Hi @mhanuel26, @shizacat, @langhaarschneider,
The stlink project now contains a st-trace utility program that will read SWO output from a target. (Run "st-trace --help" for more details.) Does this meet your needs? If not, can you explain how you would like this to work?

[Ant-ON]

@simplerobot Viewing the SWO output while debugging would be a nice touch. Currently only the semihosting is supported:

stlink/src/st-util/gdb-server.c

Lines 1423 to 1481 in 01418b5

	ret = stlink_status(sl);
	if (ret) { DLOG("Semihost: status failed\n"); }
	if (sl->core_stat == TARGET_HALTED) {
	struct stlink_reg reg;
	stm32_addr_t pc;
	stm32_addr_t addr;
	int offset = 0;
	uint16_t insn;
	if (!st->semihosting) { break; }
	ret = stlink_read_all_regs (sl, &reg);
	if (ret) { DLOG("Semihost: read_all_regs failed\n"); }
	// read PC
	pc = reg.r[15];
	// compute aligned value
	offset = pc % 4;
	addr = pc - offset;
	// read instructions (address and length must be aligned).
	ret = stlink_read_mem32(sl, addr, (offset > 2 ? 8 : 4));
	if (ret != 0) {
	DLOG("Semihost: cannot read instructions at: 0x%08x\n", addr);
	break;
	}
	memcpy(&insn, &sl->q_buf[offset], sizeof(insn));
	if (insn == 0xBEAB && !has_breakpoint(addr)) {
	ret = do_semihosting (sl, reg.r[0], reg.r[1], &reg.r[0]);
	if (ret) { DLOG("Semihost: do_semihosting failed\n"); }
	// write return value
	ret = stlink_write_reg(sl, reg.r[0], 0);
	if (ret) { DLOG("Semihost: write_reg failed for return value\n"); }
	// jump over the break instruction
	ret = stlink_write_reg(sl, reg.r[15] + 2, 15);
	if (ret) { DLOG("Semihost: write_reg failed for jumping over break\n"); }
	// continue execution
	cache_sync(sl);
	ret = stlink_run(sl, RUN_NORMAL);
	if (ret) { DLOG("Semihost: continue execution failed with stlink_run\n"); }
	} else {
	break;
	}
	}

[linuxguy123]

What is the status of SWO working with STLink (st-util) such that Cortex-Debug and uScope (RTT viewer, https://github.com/DEMCON/uscope) can use it ?

If it now does work, does one need to reflash the STLink device to make SWO work or just update st-util ?

If it doesn't work, what can I do to help the situation ?

[linuxguy123]

Hi @mhanuel26, @shizacat, @langhaarschneider, The stlink project now contains a st-trace utility program that will read SWO output from a target. (Run "st-trace --help" for more details.) Does this meet your needs? If not, can you explain how you would like this to work?

Speaking as a VSCode user, how would I configure VSCode to work with st-trace ? Let's assume I want to use uScope (https://github.com/DEMCON/uscope) as my rtt viewer.

[Nightwalker-87]

@linuxguy123 There have been no action or any efforts on this topic since the last response of @Ant-ON.
I personally can't contribute to this topic, sorry.