RISC-V Spike Simulator SDK

In the recent version of the riscv-tools and freedom-u-sdk, both of them removed the support of the spike simulator, and tutorials about running Linux on spike is using static compiled busybox, which is not suitable for real test environments. Spike is the simplest simulator of RISC-V, it has a very clear description of the instructions, you can apply your ideas and check it for a quick try. The RISC-V Spike Simulator SDK wants to help people to test design with 64-bit Linux environment on Spike easily, the basic framework is based on Freedom U SDK version 1.0.

This SDK will provide great convenience for the following people who:

• want to run upstream version Linux on Spike
• want to test design in Linux environment with modified spike, gcc and other extension in toolchain
• want to have a overview about embedded system development

This SDK follows the newest Linux Kernel, GNU toolchain and Spike, the functions of each folder in the project are as follows:

Folder	Description	Version
repo/buildroot	Build initramfs	2024.08
repo/linux	Linux Kernel	6.11.4
repo/riscv-gnu-toolchain	GNU Compiler Toolchain	gcc 14.2.0 ld 2.43.1
repo/riscv-(isa-sim,pk)	Simulator & Bootloader	master
repo/opensbi	Supervisor / Bootloader	v1.5.1
conf	config for SDK

Quickstart

Build dependencies on Ubuntu 18.04/20.04:

$ sudo apt-get install device-tree-compiler autoconf automake autotools-dev    \
curl libmpc-dev libmpfr-dev libgmp-dev gawk build-essential bison flex texinfo \
gperf libtool patchutils bc zlib1g-dev libexpat-dev python-dev python3-dev unzip \
libglib2.0-dev libpixman-1-dev git rsync wget cpio

git clone https://github.com/riscv-zju/riscv-rss-sdk.git

# For people who only want to have a try
sh quickstart.sh
# For people who want to develop the whole system
git submodule update --init --recursive --progress

#	NOTICE: 
# 		If you already have a riscv toolchain, please notice ** DO NOT SET
#		 $RISCV and MAKE SURE NO ORIGIN RISCV TOOLCHAIN IN YOUR $PATH **
make

Software Development

The default process will only build Linux cross-compiler, which has prefix "riscv64-unknown-linux", if you want using newlib, you can use make newlib to build, then you can use pk as a kernel to run your program.

The main compile process will run vmlinux on spike directly, to add your test program, you should add your elfs in ./work/buildroot_initramfs_sysroot and make again.

NOTICE: The test program should use Linux cross-compiler to compile , instead of Newlib cross-compiler.

If the benchmark you choose need some package, you can use make buildroot_initramfs-menuconfig to reconfigure buildroot and touch buildroot && make to rebuild.

Same to linux, if you want to add driver for new devices, make linux-menuconfig to reconfigure, touch linux && make to rebuild.

If you want to build step by step ...

1. Build RISC-V GNU Toolchain

   The key to build the dynamic link elf is using the correspond kernel version header to build the gnu toolchain. And if you want to use this SDK to do some development on your own chip, you may also need to change ARCH@ABI.

2. Build rootfs

   Using buildroot to help you to build a rootfs, you can add config in conf/buildroot_initramfs_config to add package, and you can copy your pre-compiled elf to rootfs/initramfs_sysroot to access in Spike. And remember, the basic idea of this SDK is to deconfig all the device, because spike is very limited support for devices, specically the Ethernet, so you should not open DHCP.

3. Compile Linux

   You can find config in work/linux_defconfig.

4. Bootloader

   You can choose between bbl or opensbi to use as bootloader to launch the simulation. Either edit the default in the Makefile or launch

   # default
   BL=opensbi make
   # or
   BL=bbl make

5. Spike

   The default account is root, here is a terminal log from Linux 5.8.0.

6. Debug via JTAG (for starship)

   You can use the openocd to debug our FPGA by the following openocd configuration file conf/starship.cfg

   	adapter speed 1000
   	adapter driver ftdi
   	ftdi vid_pid 0x0403 0x6010
   	ftdi channel 0
   	ftdi layout_init 0x00e8 0x60eb
   	reset_config none
   	transport select jtag
   	set _CHIPNAME riscv
   	jtag newtap $_CHIPNAME cpu -irlen 5
   
   	set _TARGETNAME $_CHIPNAME.cpu
   
   	target create $_TARGETNAME.0 riscv -chain-position $_TARGETNAME
   	$_TARGETNAME.0 configure -work-area-phys 0x80000000 -work-area-size 10000 -work-area-backup 1
   	riscv use_bscan_tunnel 0
   

   This configuration has been proved validly on VC707 and FTDI2332. The vid_pid is the vendor id and product id of the FTDI device, and you can get this paramter by run lsusb The ftdi channel is the channel id of the jtag channel while the ftdi USB device has 4 channel If your connection between jtag port and debug board is correct, when you run openocd -f conf/starship.cfg, the following output means your openocd connects the fpga debug module successfully.

   	Open On-Chip Debugger 0.12.0+dev-g4559b4790 (2023-12-14-15:22)
   	Licensed under GNU GPL v2
   	For bug reports, read
   			http://openocd.org/doc/doxygen/bugs.html
   	Info : Nested Tap based Bscan Tunnel Selected
   	Info : Listening on port 6666 for tcl connections
   	Info : Listening on port 4444 for telnet connections
   	Info : clock speed 1000 kHz
   	Info : JTAG tap: riscv.cpu tap/device found: 0x00000001 (mfg: 0x000 (<invalid>), part: 0x0000, ver: 0x0)
   	Info : [riscv.cpu.0] datacount=2 progbufsize=16
   	Info : [riscv.cpu.0] Disabling abstract command reads from CSRs.
   	Info : [riscv.cpu.0] Disabling abstract command writes to CSRs.
   	Info : [riscv.cpu.0] Examined RISC-V core; found 1 harts
   	Info : [riscv.cpu.0]  XLEN=64, misa=0x800000000094112d
   	[riscv.cpu.0] Target successfully examined.
   	Info : starting gdb server for riscv.cpu.0 on 3333
   	Info : Listening on port 3333 for gdb connections
   

   Then you can use gdb to debug fpga by remote connecting the 3333 port.

Finally, if you have any suggestions for this SDK, please push it !