Hi all,
This is a port of QEMU TCG to the brand-new CPU architecture LoongArch,
introduced by Loongson with their 3A5000 chips.
Everything is tested on real 3A5000 board (system emulation, linux-user,
make check) and GitLab (CI jobs), and rebased to latest master branch.
## About the series
Only the LP64D ABI is supported, as this is the only one fully
implemented and supported by Loongson so far. 32-bit support is incomplete
from outset, and removed from the very latest upstream submissions, so you
can't even configure for that.
The architecture's documentation is already translated into English;
it can be browsed at https://loongson.github.io/LoongArch-Documentation/.
The LoongArch ELF psABI doc (version 1.00) could be found at [1];
if anything is missing there, it's most likely the same as RISC-V, but
you can always raise an issue over their issue tracker at [2].
[1]:
https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html
[2]: https://github.com/loongson/LoongArch-Documentation/issues
In this series I made use of generated instruction encodings and
emitters from https://github.com/loongson-community/loongarch-opcodes
(a community project started by myself, something I must admit), as the
LoongArch encoding is highly irregular even for a fixed 32-bit ISA, and
I want to minimize the maintenance burden for future collaboration.
This series touches some of the same files as Song Gao's previous
submission of LoongArch *target* support, which is a bit unfortunate;
one of us will have to rebase after either series gets in. Actual
conflict should only happen on build system bits and include/elf.h,
though, as we're working on entirely different areas.
## How to build and test this
Upstream support for LoongArch is largely WIP for now, which means you
must apply a lot of patches if you want to even cross-build for this arch.
The main sources I used are as follows:
* binutils: (already upstream as of November 2021)
* gcc: https://github.com/xen0n/gcc/tree/for-gentoo-gcc-12-v5
based on https://github.com/loongson/gcc/tree/loongarch_upstream_v3
* glibc: https://github.com/xen0n/glibc/tree/for-gentoo-glibc-2.34-v3
based on https://github.com/loongson/glibc/tree/loongarch_2_34_dev
* Linux: https://github.com/xen0n/linux/tree/loongarch-playground-v7
based on https://github.com/loongson/linux/tree/loongarch-next
* Gentoo overlay: https://github.com/xen0n/loongson-overlay
I have made ready-to-use Gentoo stage3 tarballs, but they're served with
CDN off my personal cloud account, and I don't want the link to be
exposed so that my bills skyrocket; you can reach me off-list to get the
links if you're interested.
As for the hardware availability, the boards can already be bought in
China on Taobao, and I think some people at Loongson might be able to
arrange for testing environments, if testing on real hardware other than
mine is required before merging; they have their in-house Debian spin-off
from the early days of this architecture. Their kernel is
ABI-incompatible with the version being upstreamed and used by me, but
QEMU should work there regardless.
Lastly, I'm new to QEMU development and this is my first patch series
here; apologizes if I get anything wrong, and any help or suggestion is
certainly appreciated!
## Changelog
v11 -> v10:
- Rebased to latest development branch