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Lu Yahan edited this page Feb 14, 2023 · 59 revisions

This page describes how to build V8 for execution on RISC-V hardware or RISC-V QEMU. It is assumed that you have already followed the steps to get the source.

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RISC-V Toolchain

Install Prerequisites

sudo apt install gawk texinfo zlib1g-dev

Build Toolchain

Follow the steps below to install the RISC-V toolchain. There is nothing modified in the standard toolchain, so if you already have this installed, you can skip this step.

$ git clone https://github.com/riscv/riscv-gnu-toolchain
$ cd riscv-gnu-toolchain
$ git submodule update --init --recursive

./configure --prefix=/opt/riscv
sudo make linux -j8

Note -j8 specifies parallel build with 8 processes, and should be adjusted to the number of cores on your machines.

Be sure to add the path to this new toolchain to your path:

export PATH="/opt/riscv/bin:$PATH"

V8 Build

Install prerequisites

The following script will use apt to install any packages required for building v8. You will need sudo access to install the packages.

cd $V8_ROOT/v8
./build/install-build-deps.sh

Configure toolprefix

Make sure you have followed the Patch the Chromium Toolchain step on the Get the Source page.

Before we build it, we need to apply a patch. By default, the toolprefix of gcc_toolchain("riscv64") is set to riscv64-linux-gnu-. If your system uses a different RISC-V toolchain prefix, the setting for toolprefix needs to be manually updated. For instance, if your RISCV toolchain has the prefix of riscv64-unknown-linux-gnu, then make the following changes to $V8_ROOT/v8/build/toolchain/linux/BUILD.gn

gcc_toolchain("riscv64") {
  toolprefix = "riscv64-unknown-linux-gnu"
  ...

Cross-compile v8 as RISC-V binary on an x86-64 Host

Configure with GN

The following commands build an riscv64 executable for v8 . We use gn to configure the debug build as such:

gn gen out/riscv64.native.debug --args='is_component_build=false is_debug=true target_cpu="riscv64" v8_target_cpu="riscv64" use_goma=false goma_dir="None" treat_warnings_as_errors=false'

If the binary is too large. You can add symbol_level = 1 or symbol_level = 0 and is_debug = false to ./out/riscv64.native.debug/arg.gn. If symbol_level is 0, it means there is no debug-symbol in binary. Default value is 2.

Build with Ninja

ninja -C out/riscv64.native.debug -j8

Note, -j8 specifies to use 8 cores for the build and should be adjusted for your build machine.

Optional-Build with clang

  1. clang need riscv64-gcc-toolchain You can get it on https://github.com/riscv-collab/riscv-gnu-toolchain/tags After download riscv64-glibc-ubuntu-20.04-nightly-*-nightly.tar.gz, then tar xzvf into /path/to/riscv64/.
  2. Download patch for build and apply it
  1. Build
  • cd /PATH/to/v8/
  • gn gen out/riscv64.native.debug --args='is_clang=true use_lld=true riscv64_gcc_toolchain_path="/path/to/riscv64" riscv64_sysroot="/path/to/clang/sysroot" is_component_build=false is_debug=true target_cpu="riscv64" v8_target_cpu="riscv64" use_goma=false goma_dir="None" treat_warnings_as_errors=false'
  1. Note The above referred-to clang is built by chromium. If you want to use custom clang adding clang_base_path=/PATH/to/clang-install-dir/ into args.gn which in your build dir.

referred args.gn

clang_base_path = "/home/luyahan/clang/"
riscv_gcc_toolchain_path = "/home/luyahan/riscv64/"
riscv_sysroot = "/home/luyahan/riscv64/sysroot"
use_lld = true 
symbol_level = 0
is_component_build = false
is_clang = true
clang_use_chrome_plugins = false
target_cpu = "riscv64"
v8_target_cpu = "riscv64"
use_goma = false
goma_dir = "None"
treat_warnings_as_errors = false

Run on QEMU

Download QEMU

Clone QEMU:

cd $V8_ROOT/
git clone [email protected]:qemu/qemu.git
cd $V8_ROOT/qemu
git checkout v5.0.0

Install Prerequisites

sudo apt-get install libglib2.0-dev libpixman-1-dev

Build QEMU for riscv64

./configure --target-list=riscv64-softmmu && make -j 4
sudo make install # Optional

Download Fedora and U-Boot Images

From https://dl.fedoraproject.org/pub/alt/risc-v/repo/virt-builder-images/images/, download Fedora-Developer-Rawhide-*.raw.xz as well as the matching Fedora-Developer-Rawhide-*-fw_payload-uboot-qemu-virt-smode.elf:

wget https://dl.fedoraproject.org/pub/alt/risc-v/repo/virt-builder-images/images/Fedora-Developer-Rawhide-20191123.n.0-sda.raw.xz

unxz -k Fedora-Developer-Rawhide-20191123.n.0-sda.raw.xz

wget https://dl.fedoraproject.org/pub/alt/risc-v/repo/virt-builder-images/images/Fedora-Developer-Rawhide-20191123.n.0-fw_payload-uboot-qemu-virt-smode.elf

Run QEMU

In the command below, VER is the version number from the files you downloaded above, for example, 20191123.n.0.

Let FEDORA_IMAGE_DIR be the directory that contains Fedora-Developer-Rawhide-20191123.n.0-fw_payload-uboot-qemu-virt-smode.elf and Fedora-Developer-Rawhide-20191123.n.0-sda.raw (downloaded by following the previous step).

cd <FEDORA_IMAGE_DIR>
export VER=20191123.n.0
qemu-system-riscv64 \
  -nographic \
  -machine virt \
  -smp 4 \
  -m 2G \
  -kernel Fedora-Developer-Rawhide-${VER}-fw_payload-uboot-qemu-virt-smode.elf \
  -object rng-random,filename=/dev/urandom,id=rng0 \
  -device virtio-rng-device,rng=rng0 \
  -device virtio-blk-device,drive=hd0 \
  -drive file=Fedora-Developer-Rawhide-${VER}-sda.raw,format=raw,id=hd0 \
  -device virtio-net-device,netdev=usernet \
  -netdev user,id=usernet,hostfwd=tcp::3333-:22

Once qemu is brought up, you will see the following prompt:

Welcome to the Fedora/RISC-V disk image
https://fedoraproject.org/wiki/Architectures/RISC-V

Build date: Sat Nov 23 12:47:19 UTC 2019

Kernel 5.4.0-0.rc7.git0.1.1.riscv64.fc32.riscv64 on an riscv64 (ttyS0)

The root password is 'fedora_rocks!'.
root password logins are disabled in SSH starting Fedora 31.
User 'riscv' with password 'fedora_rocks!' in 'wheel' group is provided.

To install new packages use 'dnf install ...'

To upgrade disk image use 'dnf upgrade --best'

If DNS isn’t working, try editing ‘/etc/yum.repos.d/fedora-riscv.repo’.

For updates and latest information read:
https://fedoraproject.org/wiki/Architectures/RISC-V

Fedora/RISC-V
-------------
Koji:               http://fedora.riscv.rocks/koji/
SCM:                http://fedora.riscv.rocks:3000/
Distribution rep.:  http://fedora.riscv.rocks/repos-dist/
Koji internal rep.: http://fedora.riscv.rocks/repos/
fedora-riscv login:

The default root password for this image is fedora_rocks!.

Copy V8 to QEMU

Inside the QEMU console, you'll need to enable root login over ssh with password. Add the following line to /etc/ssh/sshd_config:

PermitRootLogin=yes

Then restart the ssh server:

[root@fedora-riscv ~]# systemctl restart sshd.service

Now, you can use scp from a regular terminal on the same machine (not the qemu terminal) to copy files to the emulated machine. Note that the SSH port of the machine is mapped to 3333.

[joesmith@your-local-terminal] scp -P 3333 $V8_ROOT/v8/out/riscv64.native.debug/d8 $V8_ROOT/v8/out/riscv64.native.debug/snapshot_blob.bin root@localhost:~/.

To log into your QEMU instance from another terminal on the same server, ssh -p 3333 root@localhost.

Run V8 on QEMU

Now, you are ready to run d8 inside the qemu console:

[root@fedora-riscv ~]# cat hello.js
console.log("hello, world!");
[root@fedora-riscv ~]# ./d8 hello.js
hello, world!

For more info about Fedora on RISC-V, please visit https://fedoraproject.org/wiki/Architectures/RISC-V/Installing

Script for Developers in China

For developers within China, the PLCT lab provides a script to retrieve and run fedora-riscv64 from a local mirror: deploy_riscv64fedora_qemu.sh.

Run this script:

./deploy_riscv64fedora_qemu.sh
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