nuttx-sg2000/README.md

![RISC-V Sophgo SG2000](https://lupyuen.github.io/images/sg2000-soc.jpg)

# Apache NuttX RTOS on 64-bit RISC-V Sophgo SG2000 (T-Head C906 / Milk-V Duo S)

64-bit RISC-V Sophgo SG2000 SoC ... Will it boot Apache NuttX RTOS? 🤔 (T-Head C906 / Milk-V Duo S)

https://www.cnx-software.com/2024/02/07/sophgo-sg2000-sg2002-ai-soc-features-risc-v-arm-8051-cores-android-linux-freertos/

Let's find out! Connect our USB UART Dongle like so...

https://milkv.io/docs/duo/getting-started/duos

![Milk-V Duo S](https://lupyuen.github.io/images/sg2000-board.jpg)

USB UART Dongle must be CP2102, it doesn't like CH340G 😬

Flip the switch so it's set to "RV" (RISC-V) instead of "Arm"...

![Switch to "RV" (RISC-V) instead of "Arm"](https://lupyuen.github.io/images/sg2000-switch.jpg)

Power up via the USB-C Port. We should see in RISC-V Mode...

https://gist.github.com/lupyuen/a7c3af98be36dcd5cc5b45f5aadc5d16

```bash
C.SCS/0/0.WD.URPL.USBI.USBEF.BS/EMMC.EMI/25000000/12000000. E:bm_emmc_send_cmd_without_data CMD: 1 INT_STAT: 0x E:bm_emmc_send_cmd_without_data CMD: 0 INT_STAT: 0x E:eMMC init failed, 3
 E:eMMC initializing failed
PS. E:bm_emmc_send_cmd_without_data CMD: 6 INT_STAT: 0x E:load param1 (-5)
 E:Boot failed (8).
 E:RESET:plat/mars/platform.c:114
WD.C.SCS/0/0.WD.URPL.USBI.USBEF.BS/EMMC.EMI/25000000/12000000. E:bm_emmc_send_cmd_without_data CMD: 1 INT_STAT: 0x E:bm_emmc_send_cmd_without_data CMD: 0 INT_STAT: 0x E:eMMC init failed, 3
 E:eMMC initializing failed
```

If we see `B.SCS` instead of `C.SCS`...

https://gist.github.com/lupyuen/d55b77a51ee8b258d6d1c0799770742a

```bash
B.SCS/0/0.WD.URPL.USBI.USBEF.BS/EMMC.EMI/25000000/12000000.
```

Nope we're in Arm Mode! Flip the switch back to RISC-V!

If we use CH340G: UART Output will be garbled...

https://gist.github.com/lupyuen/1d5ba1b2a47c110ee7ff265102b1aae5

Milk-V Duo S doesn't ship with U-Boot Bootloader preinstalled. Too bad we can't boot NuttX over TFTP, our NuttX Porting will be a bit slower. Bummer :-(

Let's boot with U-Boot + Linux on MicroSD: https://github.com/Fishwaldo/sophgo-sg200x-debian/releases

We pick the Latest Release for Duo S: https://github.com/Fishwaldo/sophgo-sg200x-debian/releases/download/v1.1.0/duos_sd.img.lz4

```bash
→ ls -l /Volumes/boot
total 17488
-rwxrwxrwx  1 Luppy  staff  3494900 Apr 24 11:33 System.map-5.10.4-20240329-1+
-rwxrwxrwx  1 Luppy  staff   125534 Apr 24 11:33 config-5.10.4-20240329-1+
drwxrwxrwx  1 Luppy  staff     2048 Apr 24 11:33 extlinux
drwxrwxrwx  1 Luppy  staff     2048 Apr 24 11:33 fdt
-rwxrwxrwx  1 Luppy  staff   388608 Apr 24 11:33 fip.bin
-rwxrwxrwx  1 Luppy  staff  4937389 Apr 24 11:33 vmlinuz-5.10.4-20240329-1+

→ ls -l /Volumes/boot/extlinux
total 4
-rwxrwxrwx  1 Luppy  staff  749 Apr 24 11:33 extlinux.conf

→ ls -l /Volumes/boot/fdt
total 4
drwxrwxrwx  1 Luppy  staff  2048 Apr 24 11:33 linux-image-duos-5.10.4-20240329-1+

→ ls -l /Volumes/boot/fdt/linux-image-duos-5.10.4-20240329-1+
total 44
-rwxrwxrwx  1 Luppy  staff  21575 Apr 24 11:33 cv181x_milkv_duos_sd.dtb
```

Here's the Boot Config...

```bash
→ cat /Volumes/boot/extlinux/extlinux.conf
## /boot/extlinux/extlinux.conf
##
## IMPORTANT WARNING
##
## The configuration of this file is generated automatically.
## Do not edit this file manually, use: u-boot-update

default l0
menu title U-Boot menu
prompt 1
timeout 50


label l0
	menu label Debian GNU/Linux trixie/sid 5.10.4-20240329-1+
	linux /vmlinuz-5.10.4-20240329-1+

	fdtdir /fdt/linux-image-duos-5.10.4-20240329-1+/

	append root=/dev/root console=ttyS0,115200 earlycon=sbi root=/dev/mmcblk0p2 rootwait rw

label l0r
	menu label Debian GNU/Linux trixie/sid 5.10.4-20240329-1+ (rescue target)
	linux /vmlinuz-5.10.4-20240329-1+

	fdtdir /fdt/linux-image-duos-5.10.4-20240329-1+/
	append root=/dev/root console=ttyS0,115200 earlycon=sbi root=/dev/mmcblk0p2 rootwait rw single
```

Yep Linux boots OK on Milk-V Duo S!

https://gist.github.com/lupyuen/01d409b7bde9607a96cd4d460e53330a

```bash
OpenSBI v0.9
   ____                    _____ ____ _____
  / __ \                  / ____|  _ \_   _|
 | |  | |_ __   ___ _ __ | (___ | |_) || |
 | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
 | |__| | |_) |  __/ | | |____) | |_) || |_
  \____/| .__/ \___|_| |_|_____/|____/_____|
        | |
        |_|

Platform Name             : Milk-V DuoS
Platform Features         : mfdeleg
Platform HART Count       : 1
Platform IPI Device       : clint
Platform Timer Device     : clint
Platform Console Device   : uart8250
Platform HSM Device       : ---
Platform SysReset Device  : ---
Firmware Base             : 0x80000000
Firmware Size             : 132 KB
Runtime SBI Version       : 0.3

Domain0 Name              : root
Domain0 Boot HART         : 0
Domain0 HARTs             : 0*
Domain0 Region00          : 0x0000000074000000-0x000000007400ffff (I)
Domain0 Region01          : 0x0000000080000000-0x000000008003ffff ()
Domain0 Region02          : 0x0000000000000000-0xffffffffffffffff (R,W,X)
Domain0 Next Address      : 0x0000000080200020
Domain0 Next Arg1         : 0x0000000080080000
Domain0 Next Mode         : S-mode
Domain0 SysReset          : yes

Boot HART ID              : 0
Boot HART Domain          : root
Boot HART ISA             : rv64imafdcvsux
Boot HART Features        : scounteren,mcounteren,time
Boot HART PMP Count       : 16
Boot HART PMP Granularity : 4096
Boot HART PMP Address Bits: 38
Boot HART MHPM Count      : 8
Boot HART MHPM Count      : 8
Boot HART MIDELEG         : 0x0000000000000222
Boot HART MEDELEG         : 0x000000000000b109
...
Debian GNU/Linux trixie/sid duos ttyS0
duos login: 
```

Let's dump the U-Boot Config...

https://gist.github.com/lupyuen/000b55a46336cddf217a589f469d60e2

```bash
U-Boot 2021.10-ga57aa1f2-dirty (Apr 24 2024 - 11:24:46 +0000) cvitek_cv181x

DRAM:  510 MiB
gd->relocaddr=0x9fbc7000. offset=0x1f9c7000
set_rtc_register_for_power
MMC:   cv-sd@4310000: 0, wifi-sd@4320000: 1
Loading Environment from nowhere... OK
In:    serial
Out:   serial
Err:   serial
Net:   
Warning: ethernet@4070000 (eth0) using random MAC address - 82:c2:1a:b2:ee:b5
eth0: ethernet@4070000
Hit any key to stop autoboot:  0
cv181x_c906# 
cv181x_c906# printenv
arch=riscv
baudrate=115200
board=mars
board_name=mars
boot_a_script=load ${devtype} ${devnum}:${distro_bootpart} ${scriptaddr} ${prefix}${script}; source ${scriptaddr}
boot_efi_binary=load ${devtype} ${devnum}:${distro_bootpart} ${kernel_addr_r} efi/boot/bootriscv64.efi; if fdt addr ${fdt_addr_r}; then bootefi ${kernel_addr_r} ${fdt_addr_r};else bootefi ${kernel_addr_r} ${fdtcontroladdr};fi
boot_efi_bootmgr=if fdt addr ${fdt_addr_r}; then bootefi bootmgr ${fdt_addr_r};else bootefi bootmgr;fi
boot_extlinux=sysboot ${devtype} ${devnum}:${distro_bootpart} any ${scriptaddr} ${prefix}${boot_syslinux_conf}
boot_prefixes=/ /boot/
boot_script_dhcp=boot.scr.uimg
boot_scripts=boot.scr.uimg boot.scr
boot_syslinux_conf=extlinux/extlinux.conf
boot_targets=mmc0 dhcp pxe 
bootcmd=run distro_bootcmd || run sdboot || run sdbootauto
bootcmd_dhcp=devtype=dhcp; if dhcp ${scriptaddr} ${boot_script_dhcp}; then source ${scriptaddr}; fi;setenv efi_fdtfile ${fdtfile}; setenv efi_old_vci ${bootp_vci};setenv efi_old_arch ${bootp_arch};setenv bootp_vci PXEClient:Arch:00027:UNDI:003000;setenv bootp_arch 0x1b;if dhcp ${kernel_addr_r}; then tftpboot ${fdt_addr_r} dtb/${efi_fdtfile};if fdt addr ${fdt_addr_r}; then bootefi ${kernel_addr_r} ${fdt_addr_r}; else bootefi ${kernel_addr_r} ${fdtcontroladdr};fi;fi;setenv bootp_vci ${efi_old_vci};setenv bootp_arch ${efi_old_arch};setenv efi_fdtfile;setenv efi_old_arch;setenv efi_old_vci;
bootcmd_mmc0=devnum=0; run mmc_boot
bootcmd_pxe=dhcp; if pxe get; then pxe boot; fi
bootdelay=1
consoledev=ttyS0
cpu=generic
distro_bootcmd=for target in ${boot_targets}; do run bootcmd_${target}; done
efi_dtb_prefixes=/ /dtb/ /dtb/current/
fdt_addr_r=0x81200000
fdtcontroladdr=9f280810
fdtfile=cv181x_milkv_duos_sd.dtb
fdtoverlay_addr_r=0x81300000
gatewayip=192.168.0.11
ipaddr=192.168.0.3
kernel_addr_r=0x80200000
kernel_comp_addr_r=0x81800000
kernel_comp_size=0x1000000
load_efi_dtb=load ${devtype} ${devnum}:${distro_bootpart} ${fdt_addr_r} ${prefix}${efi_fdtfile}
mmc_boot=if mmc dev ${devnum}; then devtype=mmc; run scan_dev_for_boot_part; fi
netdev=eth0
netmask=255.255.255.0
othbootargs=earlycon=sbi riscv.fwsz=0x80000   loglevel=9
pxefile_addr_r=0x81400000
ramdisk_addr_r=0x81600000
root=root=/dev/mmcblk0p2 rootwait rw
scan_dev_for_boot=echo Scanning ${devtype} ${devnum}:${distro_bootpart}...; for prefix in ${boot_prefixes}; do run scan_dev_for_extlinux; run scan_dev_for_scripts; done;run scan_dev_for_efi;
scan_dev_for_boot_part=part list ${devtype} ${devnum} -bootable devplist; env exists devplist || setenv devplist 1; for distro_bootpart in ${devplist}; do if fstype ${devtype} ${devnum}:${distro_bootpart} bootfstype; then run scan_dev_for_boot; fi; done; setenv devplist
scan_dev_for_efi=setenv efi_fdtfile ${fdtfile}; for prefix in ${efi_dtb_prefixes}; do if test -e ${devtype} ${devnum}:${distro_bootpart} ${prefix}${efi_fdtfile}; then run load_efi_dtb; fi;done;run boot_efi_bootmgr;if test -e ${devtype} ${devnum}:${distro_bootpart} efi/boot/bootriscv64.efi; then echo Found EFI removable media binary efi/boot/bootriscv64.efi; run boot_efi_binary; echo EFI LOAD FAILED: continuing...; fi; setenv efi_fdtfile
scan_dev_for_extlinux=if test -e ${devtype} ${devnum}:${distro_bootpart} ${prefix}${boot_syslinux_conf}; then echo Found ${prefix}${boot_syslinux_conf}; run boot_extlinux; echo SCRIPT FAILED: continuing...; fi
scan_dev_for_scripts=for script in ${boot_scripts}; do if test -e ${devtype} ${devnum}:${distro_bootpart} ${prefix}${script}; then echo Found U-Boot script ${prefix}${script}; run boot_a_script; echo SCRIPT FAILED: continuing...; fi; done
scriptaddr=0x81500000
sdboot=setenv bootargs ${reserved_mem} ${root} ${mtdparts} console=$consoledev,$baudrate $othbootargs;echo Boot from SD dev ${sddev} ...;mmc dev ${sddev} && fatload mmc ${sddev} ${uImage_addr} boot.sd;if test $? -eq 0; then bootm ${uImage_addr}#config-cv181x_milkv_duos_sd;fi;
sdbootauto=cvi_sd_boot;setenv bootargs ${reserved_mem} ${root} ${mtdparts} console=$consoledev,$baudrate $othbootargs;echo Boot from SD dev ${sddev} auto ...;mmc dev ${sddev} && fatload mmc ${sddev} ${uImage_addr} boot.sd;if test $? -eq 0; then bootm ${uImage_addr}#config-cv181x_milkv_duos_sd;fi;
sddev=0
serverip=192.168.56.101
stderr=serial
stdin=serial
stdout=serial
uImage_addr=0x81800000
update_addr=0x9fe00000
vendor=cvitek

Environment size: 4333/131068 bytes
```

Aha Ethernet Driver is available in U-Boot. Which means we can boot NuttX over TFTP yay!

TODO: Get the eMMC Version with U-Boot preinstalled. But flashing the eMMC only works on Windows. Sigh