Running an RISC-V OpenSBI simulation from scratch in Intel Simics on Ubuntu 24.04

From a fresh Ubuntu 24 distro install the following packages:

sudo apt install -y git build-essential wget cpio unzip rsync bc libncurses5-dev screen bison file flex libcanberra-gtk-*        

Then get Buildroot sources:

git clone https://github.com/buildroot/buildroot.git        

and create a new Buildroot configuration:

cd buildroot/configs        

vi simics_simple_riscv_defconfig        

Use these parameters from "Intel Simics Simulator 7 Documentation / TARGET GUIDES / RISC-V* Simple Board Target Guide / 3 Simulated Machines / 3.1.1 Building linux, bootloader, and root file system" (Documentation is included in Simics installation):

# Architecture
BR2_riscv=y
BR2_RISCV_64=y

# System
BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
BR2_SYSTEM_DHCP="eth0"

# Kernel
BR2_LINUX_KERNEL=y
BR2_LINUX_KERNEL_USE_ARCH_DEFAULT_CONFIG=y
BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.5.8"
BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_6_5=y
BR2_LINUX_KERNEL_IMAGE=y

# Boot loader
BR2_TARGET_OPENSBI=y
BR2_TARGET_OPENSBI_PLAT="generic"

# Root file system
BR2_TARGET_ROOTFS_EXT2=y

# Host packages
BR2_PACKAGE_HOST_DTC=y        

add the following additional params at the end of configuration:

# Boot loader fix: 
# Simics want ELF at address 0x80000000 
# while new SBI versions set 0x0 
# (many thanks to Gustav Wiklander)
BR2_TARGET_OPENSBI_CUSTOM_VERSION=y
BR2_TARGET_OPENSBI_CUSTOM_VERSION_VALUE="1.4"        

Now set the new Builroot configuration and compile the kernel:

cd ..        

make simics_simple_riscv_defconfig        

make -j$(nproc)        

WARNING! To access the following page you need an Intel Registration Center account. Registration is free.

Go to this page

https://lemcenter.intel.com/productDownload/?Product=256660e5-a404-4390-b436-f64324d94959

to download both

simics-7-packages-2024-41-linux64.ispm

and

intel-simics-package-manager-1.12.0-linux64.tar.gz

and then put them in your working directory (e.g. your home).

Now extract intel-simics-package-manager-1.12.0-linux64.tar.gz files and run the installation:

cd ~        

tar -zxvf intel-simics-package-manager-1.12.0-linux64.tar.gz        

./intel-simics-package-manager-1.12.0/ispm packages --install-bundle ~/simics-7-packages-2024-41-linux64.ispm --install-dir ~/simics --create-project ~/simics-projects/first        

Remember:

• --install-bundle is the location of ispm downloaded file
• --install-dir is the installation directory
• --create-project is the directory of your (first) project. To run Simics you need to have one.

After that, create the targets/risc-v-simple/images/linux directory inside your project:

mkdir -p simics-projects/first/targets/risc-v-simple/images/linux        

and copy both fw_dynamic.elf and rootfs.ext2 from Buildroot output to that directory:

cp buildroot/output/images/fw_dynamic.elf buildroot/output/images/Image buildroot/output/images/rootfs.ext2 simics-projects/first/targets/risc-v-simple/images/linux        

Now enter in your project directory and run Simics from there:

cd simics-projects/first/        

./simics        

and from Simics prompt type:

load-target target = "risc-v-simple/linux"        

run        

Et voilà! Buildroot kernel image will boot in a new output window:

Stay tuned to my next articles to get my experiences about customized processor pipelines and MMU.