Architectures/RISC-V/Bootstrapping

All about bootstrapping Fedora on RISC-V.

Introduction

Bootstrapping happens in several stages which are outlined in detail in the README and Makefile in this repository.

The general idea is that we go in stages (numbered for historical reasons):

Stage 3

Build an x86_64 disk image, but remove all the binaries and libraries from it. The binaries and libraries are cross-compiled from the host using the riscv64-unknown-linux-gnu-gcc compiler.

After building the stage 3 disk image in this way, it is bootable under qemu-system-riscv64 and has working gcc and rpmbuild:

Tue Dec 19 22:47:00 UTC 2017

Welcome to the Fedora/RISC-V stage3 disk image
https://fedoraproject.org/wiki/Architectures/RISC-V

stage3:/# ls
bin   dev  home  lib    lost+found  mnt  proc  rpmbuild  sbin  sys  usr
boot  etc  init  lib64  media       opt  root  run       srv   tmp  var
stage3:/# uname -a
Linux stage3 4.15.0-rc3-01064-g418457520fbb #2 Tue Dec 19 22:31:06 GMT 2017 riscv64 GNU/Linux
stage3:/# gcc --version
gcc (GCC) 7.2.0
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
stage3:/# rpmbuild --version
RPM version 4.12.90

Stage 4

Using the stage 3 disk image, running under qemu, we build RPMs for many core packages.

Eventually we have built enough RPMs that we can build a clean stage 4 disk image entirely from RPMs.

After stage 4

Using the clean stage 4 disk image we now go on to build the remaining packages from Fedora. This is a very long, incremental task aided by an autobuilder which picks up new packages from real Fedora and tries to build them for RISC-V. In addition we build and fix packages by hand.

How to take part

Join the #fedora-riscv IRC channel on FreeNode and say hello.

Enable Richard Jones's riscv copr and install riscv-qemu. Alternately you can build it from source in the fedora-riscv-bootstrap repo.

Check out the fedora-riscv-bootstrap repository, read the README and Makefile files, and then attempt to build it using:

make stage1
make stage2
make stage3
make boot-stage3-in-qemu

Semi-automatically building packages in stage3

This basically automates the process described in the next section.

fedpkg clone -B the_package
cd the_package/f25
# make changes to spec file if you want
fedpkg srpm

make stage3-build SRPM=/path/to/the_package.src.rpm

Manually building packages in stage3

The stage3 environment can be built from source or you can download a snapshot binary image. See above for links to git etc.

Pick a package which:

• has very few dependencies
• is written in C or C++
• is part of Fedora @Core

Grab the source RPM from the F25 branch in Koji or dist-git. Note you must use the F25 branch, because otherwise Perl doesn't work.

fedpkg clone -B the_package
cd the_package/f25
# make changes to spec file if you want
fedpkg srpm

Copy the source RPM into the stage3 disk image. The disk image must not be running when you do this:

virt-copy-in -a stage3-disk.img the_package.src.rpm /var/tmp/

Boot the disk image in qemu:

make boot-stage3-in-qemu

Inside the VM you may need to install some of the RPMs we have already built. Almost certainly you'll need make and bash:

rpm -Uvh /rpmbuild/RPMS/riscv64/{bash,make}-*.rpm --nodeps

Inside the VM you can now "install" the source RPM, which makes it available under /rpmbuild:

rpm -i /var/tmp/the_package.src.rpm
cd /rpmbuild/SPECS

You may need to disable hardened build and debuginfo by adding:

%global debug_package %{nil}
%undefine _hardened_build

to the spec file. Use vim to edit files.

You can now try building the package:

rpmbuild -ba the_package.spec --nodeps

If it builds successfully, brilliant! More usually this will require many cycles of debugging and fixing things. Removing dependencies or parts of the spec file is an option for these stage3 builds.

If you get a build, it will be in /rpmbuild inside the VM. sync and shut down the VM, then do:

virt-copy-out -a stage3-disk.img /rpmbuild ./

and the files will be downloaded to ./SRPMS and ./RPMS in the current directory. Note: Keep the source RPM too, especially if you modified it.

Add notes to the section below. Also come to #fedora-riscv and discuss where to put your built packages.