all: port to RISC-V

[tklauser]

This issue serves to track the port to the RISC-V architecture. There is an out-of-tree port at https://github.com/riscv/riscv-go based on Go 1.8 which - according to riscvarchive/riscv-go#19 - is no longer maintained and would need quite some work to be updated to the current Go tip.

Also see https://golang.org/cl/106256#message-2d9a5c5b89ad55b8b7999f794983f993649232c8 and https://groups.google.com/forum/#!searchin/golang-dev/RISC%7Csort:date/golang-dev/VpsyGdi-sQQ/FMu6IB_2CwAJ where @josharian summarized the current state of the existing port.

The GOARCH values riscv and riscv64 were reserved in https://golang.org/cl/106256. These values are already used by gccgo. Additional changes were made to debug/elf (https://golang.org/cl/107339), cmd/cgo (https://golang.org/cl/110066), cmd/dist and cmd/types (https://golang.org/cl/118618) in order be able to generate type definition files in the x/sys/unix package (https://golang.org/cl/133735).

/cc @bradfitz @ianlancetaylor @josharian

[gopherbot]

Change https://golang.org/cl/133735 mentions this issue: unix: add support for linux/riscv64

[davidlt]

/cc myself as Fedora/RISC-V maintainer.

I would be happy to incl. this into the distribution (once it compiles) and do some testing.

Thanks for raising this.

Does anyone know where I can get hardware to test on ?

New house, CPU and fgpa efforts are going on using risc-v.
Quite a turning point and opportunity for golang programmers.

Here is the main news feed on all of it:
https://riscv.org/news/

[junland]

@gedw99 At the moment SiFive is the only company that has produced a RISC-V dev board (HiFive Unleashed). One caveat to this board is the price, which is around $1,000 USD.

[hugelgupf]

cc @GanShun and @rjoleary the three of us were also about to start looking at a port. We got a couple of SiFive boards to try it out on.

[bradfitz]

@hugelgupf, when you're far enough along to want a builder set up, file a bug and copy me and I'd be more than happy to help.

[jasonmoo]

I recently starting using qemu to run a riscv fedora build. Here are the links in case it's useful for devving without a board.

https://github.com/riscv/riscv-qemu
https://fedoraproject.org/wiki/Architectures/RISC-V/Installing#Download_the_latest_disk_image
https://fedoraproject.org/wiki/Architectures/RISC-V/Installing#Boot_under_qemu

Using dnf install gccgo I've been able to build and run go apps in emulation.

[davidlt]

Just reminder that RISC-V is supported in released versions of QEMU and libvirt, which makes it easy to setup multiple VMs with management. See: https://fedoraproject.org/wiki/Architectures/RISC-V/Installing#Boot_with_libvirt

Note, that our libffi does not support Go closures thus some functionality does not work. The patch exist already, but I need to backport it to our libffi version. Should I bump priority on this?

[tklauser]

FWIW, I started rebasing the Go 1.18-based https://github.com/riscv/go-riscv to current Go tip at https://github.com/tklauser/go-riscv. It currently builds on linux/amd64 but cannot generate valid riscv64 binaries yet.

I currently lack the time and resources to really push it forward but maybe someone else working on it might find it useful.