User:Vazhnov/PlatformIO + VIM + ccls + Sipeed Longan nano RISC-V

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Intro

I'm not a developer.

For my job, I have to edit some shell and Python scripts. I use Vim + vim-syntastic + linters (pylint, shellcheck).

As a hobby, I'm trying to learn how to program in Asm and C for architecture RISC-V.

PlatformIO

PlatformIO is a popular platform with good support of multiple boards (like Arduino, STM32, …).

Warning
By default, PlatformIO sends your data to https://ssl.google-analytics.com/collect!

PlatformIO install

PlatformIO can be installed by Python's package management system pip. Here is an example how to install PlatformIO with Python virtualenv venv, to not interfere with your system:

user $python3 -m venv --system-site-packages /tmp/venv_platformio
user $source /tmp/venv_platformio/bin/activate
user $pip3 install platformio

Disable telemetry, if you want:

user $pio settings set enable_telemetry No
user $pio settings get

Test:

user $pio boards
Platform: gd32v
============================================================================================
ID                       MCU            Frequency    Flash    RAM    Name
-----------------------  -------------  -----------  -------  -----  -----------------------
gd32vf103v-eval          GD32VF103VBT6  108MHz       128KB    32KB   GD32VF103V-EVAL
sipeed-longan-nano       GD32VF103CBT6  108MHz       128KB    32KB   Sipeed Longan Nano
sipeed-longan-nano-lite  GD32VF103C8T6  108MHz       64KB     20KB   Sipeed Longan Nano Lite
wio_lite_risc-v          GD32VF103CBT6  108MHz       128KB    32KB   Wio Lite RISC-V

PlatformIO init

user $mkdir -pv /tmp/longan-sandbox && cd /tmp/longan-sandbox
user $pio project init --ide vim --board sipeed-longan-nano

When run at the first time, PlatformIO downloads:

After the last command, pio creates an empty structure + file .ccls which is important for a syntax checker(s):

FILE .ccls
clang

%c -std=gnu11 -Os -Wall -march=rv32imac -mabi=ilp32 -mcmodel=medlow -fmessage-length=0 -fsigned-char -ffunction-sections -fdata-sections -fno-common
%cpp -std=gnu++17 -Os -Wall -march=rv32imac -mabi=ilp32 -mcmodel=medlow -fmessage-length=0 -fsigned-char -ffunction-sections -fdata-sections -fno-common

-I/tmp/longan-sandbox/include
-I/tmp/longan-sandbox/src
-I/home/user/.platformio/packages/framework-gd32vf103-sdk/GD32VF103_standard_peripheral
-I/home/user/.platformio/packages/framework-gd32vf103-sdk/GD32VF103_standard_peripheral/Include
-I/home/user/.platformio/packages/framework-gd32vf103-sdk/GD32VF103_usbfs_driver
-I/home/user/.platformio/packages/framework-gd32vf103-sdk/GD32VF103_usbfs_driver/Include
-I/home/user/.platformio/packages/framework-gd32vf103-sdk/RISCV/drivers
-I/home/user/.platformio/packages/framework-gd32vf103-sdk/RISCV/env_Eclipse
-I/home/user/.platformio/packages/framework-gd32vf103-sdk/RISCV/stubs
-I/home/user/.platformio/packages/toolchain-gd32v/riscv-nuclei-elf/include/c++/9.2.0
-I/home/user/.platformio/packages/toolchain-gd32v/riscv-nuclei-elf/include/c++/9.2.0/riscv-nuclei-elf
-I/home/user/.platformio/packages/toolchain-gd32v/lib/gcc/riscv-nuclei-elf/9.2.0/include
-I/home/user/.platformio/packages/toolchain-gd32v/lib/gcc/riscv-nuclei-elf/9.2.0/include-fixed
-I/home/user/.platformio/packages/toolchain-gd32v/riscv-nuclei-elf/include

-DPLATFORMIO=50203
-DUSE_STDPERIPH_DRIVER
-DHXTAL_VALUE=8000000U

PlatformIO integration with different IDE

Inside a directory with source code, it is possible to create a file structure to help your favourite IDE to catch settings.

user $pio project init --ide [atom|clion|codeblocks|eclipse|emacs|netbeans|qtcreator|sublimetext|vim|visualstudio|vscode]

In common, PlatformIO creates such structure:

user $tree -a
.
├── .gitignore
├── include
│   └── README
├── lib
│   └── README
├── .pio
│   └── build
│       ├── project.checksum
│       └── sipeed-longan-nano
│           └── idedata.json
├── platformio.ini
├── src
└── test
    └── README

7 directories, 7 files

Differences described below:

  • --ide atom: creates configuration files .clang_complete and .gcc-flags.json,
  • --ide clion: creates configuration files CMakeLists.txt and CMakeListsPrivate.txt,
  • --ide codeblocks: creates configuration file platformio.cbp (XML),
  • --ide eclipse: creates configuration files .cproject and .project (both are XML) and a directory .settings/,
  • --ide emacs: creates a configuration file .ccls with clang options,
  • --ide netbeans: creates a configuration files nbproject/configurations.xml and nbproject/project.xml,
  • --ide qtcreator: creates a configuration file platformio.pro,
  • --ide sublimetext: creates a configuration files .ccls and platformio.sublime-project (JSON),
  • --ide vim: creates a configuration file .ccls with clang options,
  • --ide visualstudio: creates a configuration files platformio.vcxproj and platformio.vcxproj.filters (both are XML),
  • --ide vscode: creates a configuration files .vscode/c_cpp_properties.json, .vscode/extensions.json and .vscode/launch.json.

Also,

user $pio run -t compiledb

creates compilation database compile_commands.json which can be used by both ccls and clangd.

vim

When using Vim + vim-syntastic, it is hard to work with C/C++ code because of errors like 

/usr/lib/gcc/riscv64-linux-gnu/11/include/stdint.h|9 col 16 error| fatal error: stdint.h: No such file or directory [c/gcc]

Solution: use language server + LSP client. As an option, use language server dev-util/ccls + Native LSP client from app-editors/neovim.

Assembly in VIM

Attempt to open RISC-V assembly file with Vim will result with a bunch of errors: 

hello.s|4 error| Error: no such instruction: `li s1,0x10000000' [asm/gcc]
hello.s|5 error| Error: no such instruction: `la s2,message' [asm/gcc]
hello.s|6 error| Error: no such instruction: `addi s3,s2,14' [asm/gcc]
hello.s|8 error| Error: no such instruction: `lb s4,0(s2)' [asm/gcc]
hello.s|9 error| Error: no such instruction: `sb s4,0(s1)' [asm/gcc]

Because vim-syntastic tries to check syntax with system gcc, which doesn't know about RISC-V commands.

Put one of examples into any vimrc file:

  • To use RISC-V check for all assembly files:
    FILE ~/.config/nvim/filetype.vim
    augroup AsmRISCV
  autocmd FileType asm
   \ let g:syntastic_asm_generic = 1 |
   \ let b:syntastic_asm_gcc_exec = '~/.platformio/packages/toolchain-gd32v/bin/riscv-nuclei-elf-gcc'
augroup END
  • or, to use RISC-V check for some paths only:
    FILE ~/.config/nvim/filetype.vim
    augroup AsmRISCV
  autocmd FileType asm
    \ if stridx(expand("%:path"), $HOME.'/path/to/risc-v/asm/project-1/') == 0 ||
    \    stridx(expand("%:path"), $HOME.'/path/to/risc-v/asm/project-2/') == 0 |
    \   let g:syntastic_asm_generic = 1 |
    \   let b:syntastic_asm_gcc_exec = '~/.platformio/packages/toolchain-gd32v/bin/riscv-nuclei-elf-gcc' |
    \ endif
augroup END

ccls

dev-util/ccls is required by Neovim to check code syntax/style. It is still in "testing" state in Gentoo Portage, so:

root #echo "dev-util/ccls ~amd64" >> /etc/portage/package.accept_keywords
root #emerge --ask dev-util/ccls

Check:

user $ccls --version
ccls version 0.20210330
clang version 13.0.0

Neovim

app-editors/neovim v0.5 supports the Language Server Protocol (LSP), which is needed, so testing versions should be allowed:

root #echo "app-editors/neovim ~amd64" >> /etc/portage/package.accept_keywords

Install Neovim and Vim plug as it described in Neovim.

Create a configuration file:

FILE ~/.config/nvim/init.vim
call plug#begin('~/.local/share/nvim/site/plugged')
Plug 'vim-syntastic/syntastic'
Plug 'neovim/nvim-lspconfig'
call plug#end()

Run nvim, execute:

:PlugStatus
:PlugInstall
:UpdateRemotePlugins
:q

Then add a code from https://github.com/neovim/nvim-lspconfig/blob/master/doc/server_configurations.md#ccls at the end of the configuration file:

FILE ~/.config/nvim/init.vim
local lspconfig = require'lspconfig'
lspconfig.ccls.setup {
  init_options = {
    compilationDatabaseDirectory = "build";
    index = {
      threads = 0;
    };
    clang = {
      excludeArgs = { "-frounding-math"} ;
    };
  }
}

udev rules

Create an udev configuration file:

FILE /etc/udev/rules.d/99-platformio-udev.rules
# GD32V DFU Bootloader
ATTRS{idVendor}=="28e9", ATTRS{idProduct}=="0189", MODE="0666", ENV{ID_MM_DEVICE_IGNORE}="1", ENV{ID_MM_PORT_IGNORE}="1"

Or follow the official documentation: 99-platformio-udev.rules.

dfu-util

Note
PlatformIO uses its own binary from ~/.platformio/packages/tool-dfuutil/, so the step below is not mandatory.

app-mobilephone/dfu-util — device firmware update (DFU) USB programmer.

root #emerge --ask app-mobilephone/dfu-util

Check:

Boot your Sipeed Longan nano board with "Boot0" button pressed.

user $dfu-util -l
dfu-util 0.11

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2021 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

Found DFU: [28e9:0189] ver=1000, devnum=2, cfg=1, intf=0, path="5-1", alt=1, name="@Option Bytes  /0x1FFFF800/01*016 g", serial="3CBJ"
Found DFU: [28e9:0189] ver=1000, devnum=2, cfg=1, intf=0, path="5-1", alt=0, name="@Internal Flash  /0x08000000/512*002Kg", serial="3CBJ"

QEMU

Let's play with assembler without a real hardware:

FILE hello_poweroff_qemu.s
# Based on https://git.sr.ht/~matthias_t/hello-riscv/tree/master/item/src/hello.s

.section .init
.global _start
_start:
    li s1, 0x10000000 # s1 := 0x1000_0000
    la s2, message    # s2 := <message>
    addi s3, s2, 14   # s3 := s2 + 14
L1:
    lb s4, 0(s2)      # s4 := (s2)
    sb s4, 0(s1)      # (s1) := s4
    addi s2, s2, 1    # s2 := s2 + 1
    blt s2, s3, L1    # if s2 < s3, branch back to L1

    # Exit from QEMU, see QEMU sources: `hw/misc/sifive_test.c`, `include/hw/misc/sifive_test.h`.
    # Based on https://github.com/rtfb/riscv64-in-qemu/blob/master/src/baremetal-poweroff.s
    .equ FINISHER_FAIL,  0x3333
    .equ FINISHER_PASS,  0x5555
    .equ FINISHER_RESET, 0x7777
    li t0, FINISHER_PASS
    li t1, 0x100000
    sw t0, 0(t1)

# If QEMU exit doesn't work:
# Infinitive wait for interrupt — good to not heat up CPU
L2:
    wfi
    j L2

.section .data
message:
  .string "Hello, world!\n"

If binaries from PlatformIO are used:

user $export PATH="$PATH:$HOME/.platformio/packages/toolchain-gd32v/bin"

Compile:

user $riscv64-unknown-elf-as hello_poweroff_qemu.s -g -o hello_poweroff_qemu.elf

Create a file, to tell the linker we want to take manual control of the memory layout:

FILE qemu-riscv64-virt.ld
MEMORY
{
  ram (rwxai) : ORIGIN = 0x80000000, LENGTH = 0x08000000
}

Do some magic:

user $riscv64-unknown-elf-ld -T qemu-riscv64-virt.ld -o hello_poweroff_qemu_linked.elf hello_poweroff_qemu.elf

And run:

user $qemu-system-riscv64 -machine virt -bios none -kernel hello_poweroff_qemu_linked.elf -nographic
Hello, world!

Test project: gd32v-lcd

Prepare a test project:

user $git clone -b dev 'git@github.com:vazhnov/gd32v-lcd.git'
user $cd gd32v-lcd
user $pio project init --ide vim --board sipeed-longan-nano

Run neovim:

user $nvim -n -- src/main.c

Execute:

:LspInfo

You should see: 

Language client log: /home/user/.cache/nvim/lsp.log
Detected filetype:   c


Client: ccls (id: 1, pid: 5947, bufnr: [1])
 filetypes:       c, cpp, objc, objcpp
 autostart:       true
 root directory:  /tmp/longan-sandbox/gd32v-lcd
 cmd:             ccls

Configured servers list: ccls

Compile project with PlatformIO:

user $pio run
Processing sipeed-longan-nano (platform: gd32v; framework: gd32vf103-sdk; board: sipeed-longan-nano)
---------------------------------------------------------------------------------------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/gd32v/sipeed-longan-nano.html
PLATFORM: GigaDevice GD32V (1.2.1) > Sipeed Longan Nano
HARDWARE: GD32VF103CBT6 108MHz, 32KB RAM, 128KB Flash
DEBUG: Current (altera-usb-blaster) External (altera-usb-blaster, gd-link, jlink, rv-link, sipeed-rv-debugger, um232h)
PACKAGES:
 - framework-gd32vf103-sdk 1.0.0
 - tool-dfuutil 1.9.200310
 - toolchain-gd32v 9.2.0
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 0 compatible libraries
Scanning dependencies...
No dependencies
Building in release mode
Compiling .pio/build/sipeed-longan-nano/src/lcd.o
Compiling .pio/build/sipeed-longan-nano/src/led.o
Compiling .pio/build/sipeed-longan-nano/src/main.o
Compiling .pio/build/sipeed-longan-nano/src/systick.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_adc.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_bkp.o
src/lcd.c: In function 'lcd_init':
src/lcd.c:176:5: warning: implicit declaration of function 'delay_1ms' [-Wimplicit-function-declaration]
  176 |     delay_1ms(1);
      |     ^~~~~~~~~
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_can.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_crc.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_dac.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_dbg.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_dma.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_eclic.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_exmc.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_exti.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_fmc.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_fwdgt.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_gpio.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_i2c.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_pmu.o
/home/user/.platformio/packages/framework-gd32vf103-sdk/GD32VF103_standard_peripheral/Source/gd32vf103_i2c.c: In function 'i2c_flag_clear':
/home/user/.platformio/packages/framework-gd32vf103-sdk/GD32VF103_standard_peripheral/Source/gd32vf103_i2c.c:610:14: warning: variable 'temp' set but not used [-Wunused-but-set-variable]
  610 |     uint32_t temp;
      |              ^~~~
/home/user/.platformio/packages/framework-gd32vf103-sdk/GD32VF103_standard_peripheral/Source/gd32vf103_i2c.c: In function 'i2c_interrupt_flag_clear':
/home/user/.platformio/packages/framework-gd32vf103-sdk/GD32VF103_standard_peripheral/Source/gd32vf103_i2c.c:718:14: warning: variable 'temp' set but not used [-Wunused-but-set-variable]
  718 |     uint32_t temp;
      |              ^~~~
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_rcu.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_rtc.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_spi.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_timer.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_usart.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/Source/gd32vf103_wwdgt.o
Compiling .pio/build/sipeed-longan-nano/standard_peripheral/system_gd32vf103.o
Compiling .pio/build/sipeed-longan-nano/RISCV/drivers/n200_func.o
Compiling .pio/build/sipeed-longan-nano/RISCV/env_Eclipse/entry.o
Compiling .pio/build/sipeed-longan-nano/RISCV/env_Eclipse/handlers.o
Compiling .pio/build/sipeed-longan-nano/RISCV/env_Eclipse/init.o
Compiling .pio/build/sipeed-longan-nano/RISCV/env_Eclipse/start.o
Compiling .pio/build/sipeed-longan-nano/RISCV/env_Eclipse/your_printf.o
Compiling .pio/build/sipeed-longan-nano/RISCV/stubs/_exit.o
/home/user/.platformio/packages/framework-gd32vf103-sdk/RISCV/env_Eclipse/your_printf.c: In function '__wrap_printf':
/home/user/.platformio/packages/framework-gd32vf103-sdk/RISCV/env_Eclipse/your_printf.c:4:1: warning: control reaches end of non-void function [-Wreturn-type]
    4 | }
      | ^
Compiling .pio/build/sipeed-longan-nano/RISCV/stubs/close.o
Compiling .pio/build/sipeed-longan-nano/RISCV/stubs/fstat.o
Compiling .pio/build/sipeed-longan-nano/RISCV/stubs/isatty.o
Compiling .pio/build/sipeed-longan-nano/RISCV/stubs/lseek.o
Compiling .pio/build/sipeed-longan-nano/RISCV/stubs/read.o
Compiling .pio/build/sipeed-longan-nano/RISCV/stubs/sbrk.o
Compiling .pio/build/sipeed-longan-nano/RISCV/stubs/write.o
Compiling .pio/build/sipeed-longan-nano/RISCV/stubs/write_hex.o
Archiving .pio/build/sipeed-longan-nano/libRISCV.a
Indexing .pio/build/sipeed-longan-nano/libRISCV.a
Archiving .pio/build/sipeed-longan-nano/libstandard_peripheral.a
Indexing .pio/build/sipeed-longan-nano/libstandard_peripheral.a
Linking .pio/build/sipeed-longan-nano/firmware.elf
Building .pio/build/sipeed-longan-nano/firmware.bin
Checking size .pio/build/sipeed-longan-nano/firmware.elf
Adding dfu suffix to firmware.bin
Building .pio/build/sipeed-longan-nano/firmware.hex
dfu-suffix (dfu-util) 0.9

Copyright 2011-2012 Stefan Schmidt, 2013-2014 Tormod Volden
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

Suffix successfully added to file
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM:   [========= ]  85.2% (used 27926 bytes from 32768 bytes)
Flash: [=         ]   7.1% (used 9338 bytes from 131072 bytes)
================================================================= [SUCCESS] Took 2.01 seconds =================================================================

Flash the SoC (will also download and install ~/.platformio/packages/tool-openocd-gd32v):

user $pio run --target upload
Processing sipeed-longan-nano (platform: gd32v; framework: gd32vf103-sdk; board: sipeed-longan-nano)
---------------------------------------------------------------------------------------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/gd32v/sipeed-longan-nano.html
PLATFORM: GigaDevice GD32V (1.2.1) > Sipeed Longan Nano
HARDWARE: GD32VF103CBT6 108MHz, 32KB RAM, 128KB Flash
DEBUG: Current (altera-usb-blaster) External (altera-usb-blaster, gd-link, jlink, rv-link, sipeed-rv-debugger, um232h)
PACKAGES:
 - framework-gd32vf103-sdk 1.0.0
 - tool-dfuutil 1.9.200310
 - tool-gd32vflash 0.1.0
 - tool-openocd-gd32v 0.1.1
 - toolchain-gd32v 9.2.0
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 0 compatible libraries
Scanning dependencies...
No dependencies
Building in release mode
Checking size .pio/build/sipeed-longan-nano/firmware.elf
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM:   [========= ]  85.2% (used 27926 bytes from 32768 bytes)
Flash: [=         ]   7.1% (used 9338 bytes from 131072 bytes)
Configuring upload protocol...
AVAILABLE: altera-usb-blaster, dfu, gd-link, jlink, rv-link, serial, sipeed-rv-debugger, um232h
CURRENT: upload_protocol = dfu
Uploading .pio/build/sipeed-longan-nano/firmware.bin
dfu-util 0.9

Copyright 2005-2009 Weston Schmidt, Harald Welte and OpenMoko Inc.
Copyright 2010-2020 Tormod Volden and Stefan Schmidt
This program is Free Software and has ABSOLUTELY NO WARRANTY
Please report bugs to http://sourceforge.net/p/dfu-util/tickets/

Opening DFU capable USB device...
ID 28e9:0189
Run-time device DFU version 011a
Claiming USB DFU Interface...
Setting Alternate Setting #0 ...
Determining device status: state = dfuERROR, status = 10
dfuERROR, clearing status
Determining device status: state = dfuIDLE, status = 0
dfuIDLE, continuing
DFU mode device DFU version 011a
Device returned transfer size 2048
DfuSe interface name: "Internal Flash  "
Found GD32VF103, which reports a bad page size and count for its internal memory.
Fixed layout based on part number: page size 1024, count 128.
Downloading to address = 0x08000000, size = 9344

Erase   	[                         ]   0%            0 bytes
Erase   	[=====                    ]  21%         2048 bytes
Erase   	[==========               ]  43%         4096 bytes
Erase   	[================         ]  65%         6144 bytes
Erase   	[=====================    ]  87%         8192 bytes
Download	[                         ]   0%            0 bytes
Download	[=====                    ]  21%         2048 bytes
Download	[==========               ]  43%         4096 bytes
Download	[================         ]  65%         6144 bytes
Download	[=====================    ]  87%         8192 bytes
Download	[=========================] 100%         9344 bytes
Download done.
File downloaded successfully
dfu-util: dfuse_download: libusb_control_transfer returned -4
*** [upload] Error 74
================================================================= [FAILED] Took 3.21 seconds =================================================================

(error "dfuse_download: libusb_control_transfer returned -4" is OK).

Board will restart automatically with a new code, and you will see an bouncing amiga ball.

Dig inside

PlatformIO uses ~/.platformio/packages/toolchain-gd32v/bin/riscv-nuclei-elf-gcc to compile the code.

It is possible to pass additional options to the GCC with build_flags option of platformio.ini in your project. For example, lets keep all assembly source files after compilation:

FILE platformio.ini
[env:sipeed-longan-nano]
platform = gd32v
framework = gd32vf103-sdk
board = sipeed-longan-nano
monitor_speed = 115200
upload_protocol = dfu
build_flags =
  -save-temps
  -fverbose-asm

Also, let's create a disassemble of whole binary firmware:

user $~/.platformio/packages/toolchain-gd32v/bin/riscv-nuclei-elf-objdump -D -S --wide .pio/build/sipeed-longan-nano/firmware.elf > firmware.lss

See also

  • Arduino — how to prepare the toolchain, how to use Eclipse IDE;
  • RISC-V Multilib — but rv32i part is not written yet;
  • RISC-V ABIs — describe their properties: pointer sizes, compatibility, gcc flags, default linker path.

External links

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