all: port to linux/loong64

[XiaodongLoong]

Hi community,

I am from Loongson company (R & D CPU), and we have developed a new RISC CPU instruction architecture named LoongArch.

We have successfully ported linux/loongarch64 in Go version 1.15.6, and want to submit some patches to the Go community to support this port.

To support linux/loongarch64 port, we have a plan:
(1) provide a builder machine (Loongson 3A5000/2.2GHz,debian-buster / 4.19 linux-kernel) remotely.
(2) submit the patches in August (after Go 1.17 release).
(3) complete the submission and review of all patches by November and be stable state.
(4) maintain linux/loongarch64 port and builder machine for a long time.

[XiaodongLoong]

CC @rsc @rsto @ianlancetaylor

[dmitshur]

CC @golang/release.

[mengzhuo]

I think maybe "loong64"/"la64" is more appropriate since "loongarch64" is simply too loong ( pun :)

[ianlancetaylor]

This seems fine to me. Can you provide links to a description of the architecture?

I take it that you are suggesting a GOARCH value of loongarch64.

[dr2chase]

I prefer not "la64" because it might be confused with "IA64" which is the usual acronym for Intel's Itanium.
I think "loong64" is good; a GOARCH value that itself contains the substring "arch" is redundant, we don't do that for any other.

[rsc]

This proposal has been added to the active column of the proposals project
and will now be reviewed at the weekly proposal review meetings.
— rsc for the proposal review group

[XiaodongLoong]

@ianlancetaylor We will provide an architecture instruction manual in the near future and I will update a link on this issue. As you said we use GOARCH value of loongarch64 in our Go version 1.15.6.

@mengzhuo @dr2chase Thanks for your suggestion, we will consider it.

Thank you all.

[tklauser]

It seems like the instruction is MIPS64 compatible? How does Loongson differ from MIPS64?

I see that e.g. in GCC, in binutils and in the Linux kernel the architecture is handled as a variant of the MIPS/MIPS64 architecture. Could we do this in a similar way for Go and avoid having to introduce a separate GOARCH?

[XiaodongLoong]

@tklauser The Loongson you said is not the LoongArch. Loongson is an extension of MIPS64 instruction set, but LoongArch is not. LoongArch is a new RISC CPU instruction architecture.

[tklauser]

@XiaodongLoong thanks for clarifying

[XiaodongLoong]

The description of LoongArch architecture: https://github.com/loongson/LoongArch-Documentation/releases