Differences between revisions 136 and 137
Revision 136 as of 2021-05-20 16:36:01
Size: 38802
Comment: Add Nezha
Revision 137 as of 2021-05-31 03:52:33
Size: 38745
Editor: PaulWise
Comment: #riscv IRC channel moved to libera, #linux-riscv has been deprecated and is closing in favour of #riscv
Deletions are marked like this. Additions are marked like this.
Line 51: Line 51:
 * IRC (''see below for Debian-specific''): #riscv (general RISC-V discussions) and #linux-riscv (RISC-V Linux kernel development) at [[https://freenode.net/|freenode]]  * IRC (''see below for Debian-specific''): #riscv (RISC-V discussions) at [[https://libera.chat/|Libera Chat]]

This page contains details about a port of Debian for the RISC-V architecture called riscv64, for 32 bit (riscv32) see 32 bit RISC-V.

In a nutshell

What is RISC-V?

From the Wikipedia entry for RISC-V:

RISC-V (pronounced "risk-five") is an open source instruction set architecture (ISA) based on established reduced instruction set computing (RISC) principles.

In contrast to most ISAs, RISC-V is freely available for all types of use, permitting anyone to design, manufacture and sell RISC-V chips and software. While not the first open ISA, it is significant because it is designed to be useful in modern computerized devices such as warehouse-scale cloud computers, high-end mobile phones and the smallest embedded systems. Such uses demand that the designers consider both performance and power efficiency. The instruction set also has a substantial body of supporting software, which fixes the usual weakness of new instruction sets.

The project was originated in 2010 by researchers in the Computer Science Division at UC Berkeley, but many contributors are volunteers and industry workers that are unaffiliated with the university.

There are different versions of the instruction set for 32, 64 and 128 bits; operating as little-endian by default.

What is a Debian port?

In short, a port in Debian terminology means to provide the software normally available in the Debian archive (over 20,000 source packages) ready to install and run on systems based in a given computer architecture with the Linux kernel, or kernel-architecture combinations, with other kernels including GNU Mach (from GNU/Hurd) and kFreeBSD (from GNU/kFreeBSD).

See https://www.debian.org/ports/ and DebianPorts for more information.

What are the goals of this project in particular?

In this project the goal is to have Debian ready to install and run on systems implementing a variant of the RISC-V ISA:

  • Software-wise, this port targets the Linux kernel

  • Hardware-wise, the port targets the 64-bit variant, little-endian

This ISA variant is the "default flavour" recommended by the designers, and the one that seems to attract more interest for planned implementations that might become available in the next few years (development boards, possible consumer hardware or servers).

While 32-bit and 128-bit implementations are possible, there are problems with this:

  • In the context of RISC-V design, they have not been explored as deeply, and tools and resources (e.g. simulators, research cores) as not as well studied and adapted;
  • For general purpose computers, the focus shifted to 64-bit for many years already, and there isn't a lot of interest in 32-bit architectures except for specific purposes;
  • 32-bit ports in Debian already struggle to compile some large packages of the archive in the last few months/years, a problem that will become worse with time;
  • A 128-bit port is simply not realistic at this time.


Percentage of packages that build on RISC-V (grey line)

progress chart

Upstream project / Architecture

Upstream project / Community

Architecture details

Toolchain upstreaming status

  • binutils: upstreamed (2.28 is the first release with RISC-V support)
  • gcc: upstreamed (7.1 is the first release with RISC-V support)
  • glibc: upstreamed (2.27 is the first release with RISC-V support)
  • linux kernel: upstreamed (the architecture core code went into kernel 4.15; kernel 4.19 contains all drivers necessary for booting a qemu "virt" system to userland)
  • gdb: upstreamed (8.3 is the first release with support for riscv*-*-linux* targets)
  • qemu: upstreamed (2.12 is the first release with RISC-V support)


ASIC implementations, i.e. "real" CPU chips


On IndieGoGo

Based on Allwinner D1 with T-Head ?XuanTie C906 core at 1Ghz

SiFive "Freedom U540" SoC (quad-core RV64GC) / "HiFive Unleashed"

Instructions on how to install Debian on this hardware: InstallingDebianOn/SiFive/HiFiveUnleashed

At FOSDEM 2018, working production samples of the SiFive "Freedom U540" SoC (quad-core RV64GC) and a corresponding development board ("HiFive Unleashed") have been presented. A limited number of boards from the first production run has been made available in February 2018, a second production run has been done in June 2018.

Microchip "PolarFire SoC FPGA" / "PolarFire SoC FPGA Icicle Kit" (MPFS-ICICLE-KIT-ES)

Microchip offers the "Polarfire SoC FPGA" (quad-core RV64GC plus an integrated FPGA) and a corresponding development board (the "Icicle Kit") with 2GB of RAM, SD/eMMC, a PCIe slot, Gigabit Ethernet and various further I/O.

SiFive "Freedom U740" SoC / "HiFive Unmatched"

As of Q4/2020, pre-orders are open for the SiFive "HiFive Unmatched", a Mini-ITX board with a "Freedom U740" SoC (quad-core RV64GC), 16GB of RAM, SD, a PCIe slot, Gigabit Ethernet, an M.2 socket for an NVMe SSD and various further I/O.

StarFive "JH7100" SoC / BeagleBoard+Seedstudio+StarFive "BeagleV" board

Developer samples of the BeagleV single board computer have become available in Q2/2021, production models are planned to become available end of Q3/2021 or start of Q4/2021. Detailed specs for the developer samples are available on the BeagleV-Getting-Started page.


In the future further RISC-V-based ASICs are expected, among them a SoC from the lowRISC project, which has described itself as follows:

"lowRISC is a not-for-profit organisation working closely with the University of Cambridge and the open-source community.
lowRISC is creating a fully open-sourced, Linux-capable, RISC-V-based SoC, that can be used either directly or as the basis for a custom design. [...]
Our open-source SoC (System-on-a-Chip) designs will be based on the 64-bit RISC-V instruction set architecture. Volume silicon manufacture is planned as is a low-cost development board. [...]"

FPGA implementations

There are freely available softcores which can be synthesized to an FPGA, such as Rocket, a 64-bit RISC-V in-order core (optionally including an MMU and an IEEE 754-2008-compliant FPU).

Debian port information

Hardware baseline and ABI choice

The Debian port uses RV64GC as the hardware baseline and the lp64d ABI (the default ABI for RV64G systems).

Making the C extension a part of the default hardware baseline for general-purpose binary Linux distributions has been agreed upon between Fedora porters, Debian porters and members of the RISC-V foundation. According to the chairman of the board of the RISC-V foundation, the foundation will provide "a profile for standard RISC-V Unix platforms that will include C as mandatory".


Mailing list


  • irc.oftc.net / irc.debian.org (https://www.oftc.net/)

    • #debian-riscv
    • #debian-bootstrap (general port bootstrap efforts)

    • #lowRISC (not exactly Debian specific, but many interested people within Debian participate)

Bugs (BTS)

Submitting a new bug:

To: submit@bugs.debian.org
Subject: foo: FTBFS on riscv64

Package: foo
Version: 1.2.3-4
X-Debbugs-CC: debian-riscv@lists.debian.org
User: debian-riscv@lists.debian.org
Usertags: riscv64

The version of the package currently FTBFS on the riscv64 port:


Tagging an existing bug: (Don't use Control: user/usertag or User:/Usertag: to BUGNUMBER@bugs.debian.org, because they don't work.)

To: control@bugs.debian.org
Subject: riscv64 usertags for #BUGNUMBER
CC: debian-riscv@lists.debian.org

user debian-riscv@lists.debian.org
usertag BUGNUMBER + riscv64

FTBFS, packages that Fail To Build From Source (in riscv64)

Breno Leitão or other people from his team (ppc64el) created the following script, which lists packages that currently fail to build in riscv64, classifying them by number of arches in which it fails (e.g. only in riscv64 or in more than this one) or if there are pending patches or not, etc.; and with links to several related places handy to have (e.g. build logs, BTS).

So it's a nice place to start looking at things that need to be fixed.

Cross compilation

Pre-built toolchains

Since 2018-03-23 cross-toolchains targeting riscv64 are available in Debian. These include glibc and related basic libraries for riscv64 in arch:all packages. As those packages use different library paths than the corresponding "native" (i.e. arch:riscv64) packages and don't include some of the configuration that is part of their "native" counterparts, making full use of them for building packages in a multiarch configuration requires the following steps:

$ sudo dpkg --add-architecture riscv64
$ sudo apt-get install gcc-riscv64-linux-gnu g++-riscv64-linux-gnu
$ sudo sh -c "cat >/etc/ld.so.conf.d/riscv64-linux-gnu.conf <<EOF
$ sudo ln -s /usr/riscv64-linux-gnu/lib/ld-linux-riscv64-lp64d.so.1 /lib

Using pre-built toolchains with sbuild

While crossbuild-essential-riscv64 is not yet present, you can ask sbuild to instead install the cross-build dependencies explicitly. Add the following to ~/.sbuildrc:

$crossbuild_core_depends = {
riscv64 => ['gcc-riscv64-linux-gnu:native', 'g++-riscv64-linux-gnu:native', 'dpkg-cross:native'],              

And then run sbuild:

sbuild --build=amd64 --profiles=cross --host=riscv64

Building a toolchain with rebootstrap

Another option of getting a Debian multiarch-capable cross-toolchain for riscv64 is to build one locally with rebootstrap:

$ sudo apt-get install pbuilder
$ sudo pbuilder create --distribution unstable
$ git clone https://salsa.debian.org/helmutg/rebootstrap.git
$ cd rebootstrap
$ mkdir -p /tmp/repo && sudo pbuilder execute --bindmounts /tmp/repo bootstrap.sh HOST_ARCH=riscv64 REPODIR=/tmp/repo

As pbuilder works in a throwaway chroot and deletes it again after it has finished, it is important to bind-mount the directory into which the created packages are to be placed ("/tmp/repo" in the example above) from the host filesystem into the chroot, as otherwise the freshly built packages would be deleted again when pbuilder removes the throwaway chroot. This can be achieved by either passing a "--bindmounts" parameter to pbuilder as above or by adding a BINDMOUNTS entry to pbuilderrc.

After the build process has finished, you can find a repository with a cross-toolchain and a number of cross-built packages in /tmp/repo. Don't worry when rebootstrap stops the build process with an error - that is expected as rebootstrap tries to build further packages after the toolchain is ready and some of those don't yet properly cross-build for riscv64.

Please note that you have to delete the repository directory ("/tmp/repo" in the example above) if you want to re-run rebootstrap as rebootstrap currently doesn't properly handle a pre-filled repository directory.


Starting from 2018-03-09, upstream qemu git contains RISC-V support; since 2018-04-12 RISC-V support is available in the qemu packages in unstable.

In system-emulation mode, qemu implements a "virt" board that allows running upstream kernels with virtio block and network devices and a serial console, and a "spike"-compatible board. For user-mode emulation, the the Linux kernel provides a very useful "binfmt-misc" feature that allows to transparently run foreign-architecture user-mode binaries with qemu.

Installing qemu from the Debian archive

For using full system-emulation install the qemu-system-misc package, for transparent user-mode emulation (e.g. in a chroot) install the binfmt-support and qemu-user-static packages.

  apt install qemu-system-misc qemu-user-static binfmt-support

Manual qemu-user installation

If you don't want to use the Debian qemu packages, a static qemu for user-mode emulation can be built from upstream git as follows:

$ git clone https://git.qemu.org/git/qemu.git
$ cd qemu
$ ./configure --static --disable-system --target-list=riscv64-linux-user
$ make
$ sudo cp riscv64-linux-user/qemu-riscv64 /usr/bin/qemu-riscv64-static

Create a binfmt-support config file and register it:

$ cat >/tmp/qemu-riscv64 <<EOF
package qemu-user-static 
type magic
offset 0
magic \x7f\x45\x4c\x46\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xf3\x00
mask \xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff
interpreter /usr/bin/qemu-riscv64-static
$ sudo update-binfmts --import /tmp/qemu-riscv64

With this it is now possibe to transparantly run user-mode riscv64 binaries on another architecture:

$ uname -m
$ file busybox 
busybox: ELF 64-bit LSB executable, UCB RISC-V, version 1 (SYSV), statically linked, for GNU/Linux 3.0.0, stripped
$ ./busybox touch foo
$ ls foo

This also works in chroots if the /usr/bin/qemu-riscv64-static binary is available inside the chroot.

For the use of qemu in the bootstrap process of other ports, please see

Package repository

The Debian-Ports repository is the main package repository for the Debian riscv64 port - unless there are special circumstances, this is the repository that should be used as the base for further work on the port. A basic set of riscv64 packages has been imported into Debian-Ports on the weekend of 2018-03-24/25 and there are autobuilders running to keep the repository up-to-date.

For accessing the Debian-Ports repository, please follow the instructions at https://www.ports.debian.org/archive. Example /etc/apt/sources.list:

 deb http://ftp.ports.debian.org/debian-ports/ sid main
 deb http://ftp.ports.debian.org/debian-ports/ unreleased main
 deb-src http://ftp.ports.debian.org/debian-ports/ sid main

Mirrors are available (please use them if possible): https://www.ports.debian.org/mirrors

For information about previously used historic package repositories please refer to the Attic page.

Creating a riscv64 chroot

The "standard" way of creating a chroot in Debian is by running debootstrap. Unfortunately debootstrap has one serious limitation, and that is that it can only work with a single suite (e.g. unstable). For riscv64 this has posed a problem for quite some time because there were a number of RISC-V-specific patches for packages that were only available in the "unreleased" suite, but not in the "unstable" suite. Therefore for a long time debootstrap couldn't create a fully-working riscv64 chroot of the type "standard", although creating chroots of the types "minbase" and "buildd" worked, but since 2019-05-29 everything that is required for creating a chroot of type "standard" with debootstrap is now available in unstable.

An alternative to debootstrap is mmdebstrap, which can create a chroot from packages distributed over multiple suites while providing a largely debootstrap-compatible user interface. Unless there are specific reasons for using debootstrap, the use of mmdebstrap is therefore recommended.


To create a riscv64 chroot in /tmp/riscv64-chroot with mmdebstrap, perform the following steps:

$ sudo apt install mmdebstrap qemu-user-static binfmt-support debian-ports-archive-keyring
$ sudo mmdebstrap --architectures=riscv64 --include="debian-ports-archive-keyring" sid /tmp/riscv64-chroot "deb http://deb.debian.org/debian-ports/ sid main" "deb http://deb.debian.org/debian-ports/ unreleased main"


To create a "standard" chroot in /tmp/riscv64-chroot with debootstrap, execute the following commands:

sudo apt-get install debootstrap qemu-user-static binfmt-support debian-ports-archive-keyring
sudo debootstrap --arch=riscv64 --keyring /usr/share/keyrings/debian-ports-archive-keyring.gpg --include=debian-ports-archive-keyring unstable /tmp/riscv64-chroot http://deb.debian.org/debian-ports

Preparing the chroot for use in a virtual machine

After a basic chroot has been created in /tmp/riscv64-chroot, some further steps are necessary to prepare it as the base for a virtual machine:

$ sudo chroot /tmp/riscv64-chroot
# Update package information
apt-get update
# Set up basic networking
cat >>/etc/network/interfaces <<EOF
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
# Set root password
# Disable the getty on hvc0 as hvc0 and ttyS0 share the same console device in qemu.
ln -sf /dev/null /etc/systemd/system/serial-getty@hvc0.service  
# Install kernel and bootloader infrastructure
apt-get install linux-image-riscv64 u-boot-menu
# Install and configure ntp tools
apt-get install openntpd ntpdate
sed -i 's/^DAEMON_OPTS="/DAEMON_OPTS="-s /' /etc/default/openntpd
# Configure syslinux-style boot menu
cat >>/etc/default/u-boot <<EOF
U_BOOT_PARAMETERS="rw noquiet root=/dev/vda1"

Setting up a riscv64 virtual machine

  1. Install qemu-system-misc, opensbi and u-boot-qemu from unstable.

  2. Create a chroot.

  3. Create a disk image for qemu from the previously-created chroot in /tmp/riscv64-chroot with
    sudo apt-get install libguestfs-tools
    sudo virt-make-fs --partition=gpt --type=ext4 --size=10G /tmp/riscv64-chroot/ rootfs.img
    sudo chown ${USER} rootfs.img
  4. Run qemu-system-riscv64 with OpenSBI, U-Boot and the disk image:
    qemu-system-riscv64 -nographic -machine virt -m 1.9G \
     -bios /usr/lib/riscv64-linux-gnu/opensbi/generic/fw_jump.elf \
     -kernel /usr/lib/u-boot/qemu-riscv64_smode/uboot.elf \
     -object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-device,rng=rng0 \
     -append "console=ttyS0 rw root=/dev/vda1" \
     -device virtio-blk-device,drive=hd0 -drive file=rootfs.img,format=raw,id=hd0 \
     -device virtio-net-device,netdev=usernet -netdev user,id=usernet,hostfwd=tcp::22222-:22
    This uses qemu's "usernet" implementation which provides the virtual machine with NATed network access to the outside and works without root privileges, but it is rather slow and doesn't support all network protocols (ICMP support is limited). The "hostfwd" parameter sets up a port forwarding from port 22222 on the host to port 22 inside the virtual machine so that it is possible to log into the VM from the host.

buildd (build-daemon) information


Currently there are no porterboxes available. Please refer to the "Setting up a riscv64 virtual machine" or "OS / filesystem images" sections for installing a riscv64 virtual machine locally.

OS / filesystem images

Experimental development images are created weekly by DQIB for RISC-V, as well as for other Debian architectures. Please report bugs to GiovanniMascellani.

There is also a minimal tarball that can be used for quick installation, at least as evaluation (signed with ManuelMontecelo's key):

Once the file is downloaded and unpacked, for example in the "HiFive Unleashed" Board (most or all operations need "root" from the main OS):

# mount 2nd partition of SD card
mount /dev/mmcblk0p2 /mnt

# unpack under /mnt
cd /mnt && tar xvf DOWNLOADED_TAR

# from the main OS, chroot into it
chroot /mnt/debian-riscv64-tarball-20180418 /bin/bash -l

# set date with good precision, recent versions of "apt" are strict about time validity of repositories, and remind the timezone differences!
date -s -d'2018-05-07T21:28:57'

# add some nameserver to /etc/resolv.conf, use a local one if you can
cat <<EOF > /etc/resolv.conf

# mount virtual filesystems
mount -t sysfs sysfs /sys/
mount -t proc proc /proc
mount -t devtmpfs udev /dev/
mkdir -p /dev/pts
mount -t devpts devpts /dev/pts
mount -t tmpfs tmpfs /run
mkdir -p /run/lock

# update apt and install software
# /etc/apt/sources.list has to be edited to point to "debian ports":
# https://wiki.debian.org/RISC-V#Debian-Ports_Repository
cat <<EOF > /etc/apt/sources.list
deb http://ftp.ports.debian.org/debian-ports/ sid main
deb http://ftp.ports.debian.org/debian-ports/ unreleased main
deb-src http://ftp.ports.debian.org/debian-ports/ sid main

apt update
apt install emacs25-nox openssh-server

# (re)start openssh-server if necessary
service ssh restart

# log through ssh from another host, enjoy and be merry :-)

With this file unpacked one can easily create an image to use with Qemu or similar, but still an external kernel is needed.

Status Log

A new kernel package (linux-image-5.2.0-1-riscv64) that includes a backport of the new RISC-V kernel image header from kernel 5.3 has entered unstable. Together with OpenSBI (in unstable) and u-boot-qemu (in experimental) this allows using syslinux-style menus in U-Boot and makes setting up a virtual riscv64 system a lot easier.
With version 0.176-1.1 elfutils has moved from unreleased to unstable which makes it now possible to use debootstrap to create a riscv64 chroot of type "standard".

OpenSBI is now available from experimental.


U-Boot version 2019.07~rc1+dfsg-3 includes u-boot-sifive and u-boot-qemu package, which ship the sifive_fu540, qemu-riscv64, and qemu-riscv64_smode targets. The qemu-riscv64_smode target has been tested to work with qemu+opensbi to boot linux.

Starting with version 4.19.13-1, the regular Linux kernel packages in unstable have riscv64 support and provide a kernel image that can be booted in qemu. There has also been progress on the issue of debootstrapping a riscv64 system - while creating a "standard" chroot with debootstrap still fails due to an upstream issue in elfutils, it is now possible to use debootstrap for creating chroots in the "minbase" and "buildd" variants. As a result, sbuild now works out-of-the-box on riscv64.

Starting with version 3.2.1-9, libffi6 contains a backport of the riscv64 support from the upstream libffi7 development repository. The Debian riscv64 port had originally used a libffi7 snapshot instead of libffi6 because libffi6 didn't have any RISC-V support at that time and libffi upstream had originally planned to release libffi7 in May 2018. Based on this release schedule, all Debian architectures would have moved to libffi7 before the Buster freeze. In the meantime the upstream libffi7 release has been deferred for an unknown amount of time and riscv64 support for libffi6 has become available. Therefore the Debian riscv64 port moves from using libffi7 to using libffi6 to bring it in line with the other Debian ports. Due to ABI differences between libffi6 and libffi7, the transition requires re-building all packages that link against libffi, which will cause some packages to be temporarily uninstallable.


A fix for the broken initrd handling in the Linux kernel has been committed to the upstream kernel git repository and will be part of the 4.19rc4 release. First versions of a patchset to support the qemu RISC-V "virt" board in u-boot have been posted to the upstream u-boot development list.


The last driver bits required for booting the mainline kernel to userland on a qemu "virt" machine have been merged during the Linux 4.19 merge window. It is now possible to build a working kernel directly from upstream git without any additional patches. Please note that this currently only works for a "static" kernel, i.e. without initrd. Initrd support requires an additional patch that is planned to go upstream later in the 4.19 development cycle.

Debian 9.5 has been released on 2018-07-14 and dak now accepts packages with riscv64 in their control file. As a result, a number of essential packages have been moved from the "unreleased" to the "unstable" suite and it is now possible to use debootstrap to create a "minbase" riscv64 chroot.

The dpkg/stable update that is necessary to make dak accept packages which explicitly list riscv64 in their control file has been accepted into stable-proposed-updates and will be part of the upcoming 9.5 stable release. Once the 9.5 release is out and the system running dak has been updated accordingly, it will be possible to move essential packages like linux and glibc from unreleased to unstable and thereby enable the use of debootstrap for riscv64.


Qemu 2.12 with RISC-V support has been released on 2018-04-24.

Qemu 2.12rc3 with RISC-V support has been uploaded to unstable on 2018-04-12.

We have now both gcc-7-based as well as gcc-8-based cross-toolchains for riscv64 in unstable.


Port added to debian-ports, the first automatic builds start to build packages after the initial seed of the minimal set.


The upstream qemu maintainers have accepted the RISC-V patchset.


The dpkg 1.18.25 update for stable that would (among other things) have made the riscv64 architecture known to dak - and thereby have allowed uploads of packages that mention riscv64 in their control file to the archive - has been rejected by the stable release managers. The rejection hasn't been because of the riscv64 support but because of other factors, but it means it will unfortunately still take some time before we will be able to upload a number of core packages (e.g. linux and glibc) with riscv64 support enabled to the main archive.


A pull request to include RISC-V support into upstream qemu has been sent.


Cross-binutils targeting RV64 are now available in unstable/testing and version 5 of the qemu upstreaming patchset has been posted to the qemu-devel mailinglist.


Glibc 2.27 has been released with support for RV64. Support for RV32 hasn't been fully ready in time for the 2.27 release and will be added later on. A Debian package of glibc 2.27 has been uploaded to experimental.

Since version dpkg includes support for the riscv64 architecture. Uploading of packages that reference riscv64 in their control file to the archive isn't yet possible though, as the Debian archive management software runs on Debian/stable and a corresponding stable update is still pending.

Version 4 of the qemu upstreaming patchset has been posted to the qemu-devel mailinglist.

Support in glibc has been accepted and committed in the master branch, the release of glibc 2.27 should happen in the next few days.
Linux 4.15 was released a few days ago as well, with support for the userspace ABI needed by glibc. Drivers for this arch will be left for future releases, but ABI was the most important part.

A first version of the qemu upstreaming patchset has been posted to the qemu-devel mailinglist.


A new version of the glibc upstreaming patchset which matches the kernel code in Linux 4.15rc3 has been posted to the libc-alpha list.


The pull request for the kernel has been accepted and the architecture-core patchset has been merged into the upstream kernel repository.


A pull request for inclusion of the RISC-V architecture-core patchset into kernel 4.15 has been sent to Linus Torvalds.


The RISC-V Linux kernel upstreaming patchset has been included into linux-next.


Version 9 of the kernel upstreaming patchset has been posted to LKML on 2017-09-26. As planned after v8, it has been split into an architecture-core and a driver patchset. The RISC-V architecture maintainer has a kernel.org account now, which is a prerequisite for getting the patches into linux-next, but the actual inclusion into linux-next is still pending as the linux-next maintainer has announced that updating the linux-next tree will be on hold during the whole of October 2017.


The kernel upstreaming patchset hasn't made it in into the kernel 4.14 merge window, so it now targets kernel 4.15. Version 8 of the patchset has been posted to LKML recently (note: the archive of the corresponding thread on lkml.org appears to be incomplete). While the patchset has received an overall positive review from kernel developer Arnd Bergmann, he and two other kernel developers have pointed out a few minor points that require some further discussion and probably some restructuring of the timer code. The plan for version 9 of the patchset is to address those issues and split the patchset into an architecture-core and a driver patchset. The architecture-core patchset can then hopefully be soon included in linux-next as a preparation for getting it merged during the kernel 4.15 merge window.

The RISC-V upstream kernel patchset has gone through a number of review cycles, but hasn't made it into the kernel 4.13 merge window. Judging from the review comments, chances for an inclusion into kernel 4.14 look quite good, though. There are a number of open questions concering the RISC-V memory model, whose formal specification is still work-in-progress. The corresponding RISC-V foundation working group has announced that the formal memory model specification should be published in the near future (before end of 2017).
The upstream glibc maintainers have made clear that they require the kernel port to be accepted (at least as part of linux-next, preferably as part of a Linux release candidate) before the glibc support can be accepted for upstream inclusion. As a result, the upcoming glibc 2.26 release won't have RISC-V support. The earliest upstream glibc version that could have RISC-V support will therefore be 2.27, which is planned to be released around 02/2018.

The first version of an upstreaming patchset for glibc has been posted to the upstream glibc development list (libc-alpha).


The first version of an upstreaming patchset for the Linux kernel has been posted to the upstream Linux kernel mailinglist.


Upstream GCC 7.1 has been released with RISC-V support.


Unofficial repository published (WIP, incomplete and probably not working for you at the moment): http://riscv.mit.edu/

More information about details and story in https://people.debian.org/~mafm/posts/2017/20170422_debian-gnulinux-port-for-risc-v-64-bit-riscv64/

Upstream binutils 2.28 have been released with RISC-V support on 2017-03-02.

The GCC support for RISC-V has been committed to the upstream GCC repository and will be part of the GCC 7 release. Commit list: 1 2 3 4 5 6

The binutils support for RISC-V has been accepted upstream in November/December 2016 and will be part of binutils 2.28 (expected to be released in Q1/2017).

The GCC support for RISC-V has been accepted for upstream inclusion by the GCC Steering Committee but is still pending the final stages of the technical review as there have been a number of review comments that need to be addressed in a new version of the upstreaming patchset. There is reason for hoping that the RISC-V support could make it into the GCC 7 release, but this depends on how fast the review process can be finished.

The preparations for this port started in private a while ago, but nothing has been made public so far and nothing useful yet for users and developers.

The main reason is the lack of official support for this architecture in fundamental pieces of the toolchain (binutils, gcc, glibc), the main OS kernel (linux) or even other software that might help with the port (e.g. qemu). All of the mentioned pieces have support in progress and are considered to submit for upstreaming, but nothing definitive has happened at the moment.

In particular, a recent message informed about some upcoming changes to the supervisor specifications (the ABI), which will affect binutils at least. Starting a Debian port without the ISA being settled is not very good, since the effort will need to be restarted from scratch.

It is expected that this situation will change soon (within few months) and that progress on this port can be resumed.



Hardware Sponsors:

  • Bytemark provides hardware to help to kick-start this port. Bytemark is a long-time partner of Debian

  • Also using personal computers and regular Debian infrastructure


Created page of the port in the wiki