Duo now supports big and little cores?Come and play!Milk-V Duo, start！

kkkkk · October 20, 2023, 11:52am

Firmware version 1.05 is released. In addition to the most significant update, which is the support for the little core (C906@700MHz), the wiringX library is also ready. Grab your DFRobot sensors and start playing with them!

FreeRTOS is waiting for you, my friend!

The RTOS documentation is rapidly expanding: Introduction | Milk-V

You can find the firmware here: Releases · milkv-duo/duo-buildroot-sdk · GitHub

Good news: Under the leadership of @Pandora (junqiang) from PLCT, dual-core communication is also rapidly improving.

Change log V1.0.5

Added support for IPV6.
Replaced the cvi_pinmux command with duo-pinmux. More information available here.
Reordered the pin numbers in wiringX and python-pinong library.
Released the generic FreeRTOS code for the second core (little one).

Display:
The small core and the big core share UART0, and the information printed by the small core can be seen in the boot log.

Q&A:

Can OpenSBI boot the dual-core system?
Answer: FSBL initiates the boot process; it does not go through OpenSBI.
@AnonymousUser1: FSBL itself already supports dual-core startup, and you can use kernel remoteproc to start the small core’s ELF.
@AnonymousUser2: BL2 will first load the FreeRTOS binary from the flash into memory and start the small core. After that, BL2 loads OpenSBI/U-Boot/Kernel to run on the big core.
@AnonymousUser3: I previously learned that you can bundle the loader for the small core into the fast_image_mcu region of fip.bin (not exceeding 24k). In this case, during startup, the small core will load this part of the program.

mtuxpe · October 20, 2023, 6:35pm

Thanks for sharing @kkkkk

cwt · October 25, 2023, 8:33am

Sorry, but I quite not understand where the FreeRTOS binary stored. Is it in the SD partition or somewhere?

Sandor · October 28, 2023, 12:57pm

yes, since you use the sd card(buildroot in your card) to boot the system

Trong_Vu · November 14, 2023, 7:59am

Hi, related to these points in QnA section of your post:
“FSBL itself already supports dual-core startup”
“BL2 will first load the FreeRTOS binary from the flash into memory and start the small core”

I just can not find any line of code do the above steps in the FSBL/BL2 in Milk-V Duo buildroot SDK. I refer to this BL2 file, but it calls to pre-built objects.

github.com

milkv-duo/duo-buildroot-sdk/blob/develop/fsbl/plat/cv180x/bl2/bl2_main.c

#include <debug.h>
#include <console.h>
#include <platform.h>
#include <bl2.h>
#include <string.h>
#include <delay_timer.h>

#ifdef RTOS_ENABLE_FREERTOS
int init_comm_info(int ret)
{
	struct transfer_config_t *transfer_config = (struct transfer_config_t *)MAILBOX_FIELD;
	struct transfer_config_t transfer_config_s;
	unsigned char *ptr = (unsigned char *)&transfer_config_s;
	unsigned short checksum = 0;
	/* mailbox field is 4 byte write access, and can not access byte by byte.
	 * so init parameters and copy all to mailbox field together.
	 */
	transfer_config_s.conf_magic = RTOS_MAGIC_HEADER;
	transfer_config_s.conf_size = ((uint64_t)&transfer_config_s.checksum - (uint64_t)&transfer_config_s.conf_magic);
	transfer_config_s.isp_buffer_addr = CVIMMAP_ISP_MEM_BASE_ADDR;

This file has been truncated. show original

Where can I get the full source to to understand how BL2 load the FreeRTOS and wake up the small core?

Is there any document should I look at for better understaning the boot up of dual-core system?

Thanks ^^

Freireg · November 22, 2023, 1:01pm

Very nice post!
Any chance to update the tasks without the need to rebuild the whole image? And how to use the wiringX lib with the small core?

boondocker · February 9, 2024, 6:52pm

Is there more information on using remoteproc? There doesn’t seem to be anything in duo-buildroot-sdk/linux_5.10/drivers/remoteproc related to cvi