A plan for Fedora/RISC-V ---------------------------------------------------------------------- by Richard W.M. Jones (rjones@redhat.com) Project home page: https://fedoraproject.org/wiki/Architectures/RISC-V The aim of the project ---------------------- Get Fedora running on the RISC-V architecture! This will just be an initial pass, which we're calling an "experimental architecture". It won't even be a secondary architecture for perhaps 1 to 3 years. About Fedora: https://getfedora.org/ About RISC-V: https://riscv.org/ https://en.wikipedia.org/wiki/RISC-V lowRISC: http://www.lowrisc.org/ How do we expect people to consume Fedora/RISC-V? ------------------------------------------------- Most users will download binaries. Of course source will be available for [almost*] everything, buildable from source RPMS. Currently no hardware is available, so you either have to run RISC-V on an FPGA, or use QEMU/Spike emulation. For the FPGA option, you will need a Nexys 4 DDR development kit costing around US$341, plus an ordinary micro SD card (8+ GB), plus a host Fedora/x86-64 computer. - Maximum system RAM is 128 MB (1 GB is available if you use the other far more expensive FPGA development kit) - There is a 115200 bps 8n1 serial port. - There is no ethernet and no display. For the QEMU emulation option, see below. - QEMU has unlimited system RAM. - Network access is available. For the Spike emulation option, see below. - Spike has unlimited system RAM. - No network. [*] Some CPU peripherals use proprietary IP. The aim is to replace these with open equivalents eventually. Building the FPGA bitstream will require proprietary tools, although the source itself is free software. What parts of Fedora are we aiming to build? -------------------------------------------- The @Core packages (as RPMs), rpmbuild, gcc, and a bootable binary disk image. Only 64 bit RISC-V will be targeted. Once those are done, we can declare victory. What parts of Fedora are we *not* aiming to build? -------------------------------------------------- Nothing outside @Core except for specific compilers and build tools. Not Anaconda. Not Koji (at least, not at first). Not Grub nor EDK2. We will initially use the Berkeley bootloader (bbl), but aim for a standard bootloader later. Where will we build it? ----------------------- The packages which are run on the host (x86-64) computer will be built in COPR (https://copr.fedorainfracloud.org/). However the majority of packages will be built on RISC-V itself. Since there are no RISC-V builders, and we cannot really provide them, initially developers will be building them on their own FPGAs / emulators and uploading them. Getting build infrastructure would be a more long-term aim. Bootstrapping stages -------------------- [See also: https://fedoraproject.org/wiki/Architectures/AArch64/Bootstrap] * Stage 1 (1a) riscv-qemu.x86_64: QEMU + RISC-V system emulation Not upstream, fork of qemu 2.5.0. https://github.com/riscv/riscv-qemu Status: done http://copr-fe.cloud.fedoraproject.org/coprs/rjones/riscv Note this package runs on x86-64 hosts, and is intended for people who want to run Fedora/RISC-V but who do not have FPGA/hardware. (1b) riscv-isa-sim.x86_64: Spike system emulator Since QEMU is broken at the moment, we must use the slower Spike emulator instead. (1c) Nexys4 DDR FPGA Various sources, see: http://www.lowrisc.org/docs/untether-v0.2/fpga-demo/ * Stage 2 (2a) GNU cross-compiler toolchain. https://github.com/lowRISC/riscv-gnu-toolchain Status: done http://copr-fe.cloud.fedoraproject.org/coprs/rjones/riscv (2b) Berkley Bootloader (bbl) https://github.com/lowrisc/riscv-pk.git Status: done http://copr-fe.cloud.fedoraproject.org/coprs/rjones/riscv Used to boot the kernel and mount the root filesystem on FPGAs and QEMU. * Stage 3 (3a) kernel.riscv64: The Linux kernel, cross-compiled. Current status: Not upstream, fork of Linux 4.6. https://github.com/lowrisc/riscv-linux (3b) "Just enough userspace" The following packages, cross-compiled from x86-64 host to riscv64 target filesystem. The aim is to have a filesystem (not RPMs) that can be booted on RISC-V hardware or under QEMU, which will be sufficient to use to compile RPMs. bash.riscv64 glibc.riscv64 binutils.riscv64 gcc.riscv64 cpp.riscv64 rpm.riscv64 coreutils.riscv64 filesystem.riscv64 (?) gawk.riscv64 grep.riscv64 gzip.riscv64 sed.riscv64 xz.riscv64 zlib.riscv64 We will also need to add the following noarch packages (these do not need to be compiled, they can just be copied from another Fedora system): basesystem.noarch ca-certificates.noarch crypto-policies.noarch emacs-filesystem.noarch fedora-release.noarch fedora-repos.noarch setup.noarch tzdata.noarch ==== At this point, Fedora on RISC-V will be self-hosting ==== * Stage 4 (4a) kernel.riscv64: The Linux kernel, compiled as an RPM on RISC-V. (4b) Userspace RPMs (See the above list of packages, but built from SRPMs) (4c) Recreate the filesystem from RPMs. Distribute an initial bootable binary disk image which is completely built from RPMs (but note, not created by Anaconda). (4d) Continue compiling all other RPMs from @Core. As more packages are compiled, distribute them as RPMs and distribute updated bootable binary disk image. (4e) Declare victory and celebrate! Open issues ----------- What architecture string to use (eg. in RPM package names)? There are 32, 64 and (in theory) 128 bit variants of RISC-V. GNU uses "riscv64".