Allwinner D1 Linux Upstream Efforts - Progress?

[Gareth Halfacree]

Good morning, all.

I'm hoping someone can point me in the direction of the latest
discussions on support for the D1 (and the new SiP F133, which
includes 64MB of RAM) and/or the C906/910 in mainline Linux - prompted
by a discussion on Twitter with Bruce Hoult.

My understanding, which I will be happily corrected on if any point is wrong:

* The D1 implements RV64GC and Privileged Spec. 1.0 just fine
* The D1 implements v0.7.1 of the Vector Extensions, which is not
directly compatible with v1.0
* The D1 includes non-standard vendor-specific extensions, including
acceleration instructions

Concerns as to how support can be added in mainline Linux were raised
at the LPC:
https://www.youtube.com/watch?v=eFKvGBh5KAg&t=9535s

and have also been discussed on the RISC-V Software list:
https://lists.riscv.org/g/software/message/131
https://lists.riscv.org/g/software/message/132
https://lists.riscv.org/g/software/message/134

and it's currently not clear (to me):

* Who should be and/or is working on writing and submitting patches upstream
* Whether the patches will be accepted into Linux

I'm especially interested in the latter, and would be very
appreciative if anyone has any information on that front - I've seen
too many clever SoCs and/or SBCs fall by the wayside because support
was never mainlined and the vendor lost interest. I've a drawer full
of 'em, in fact!

Thanks in advance for any information anyone can offer.

-Gareth

[Drew Fustini]

I've CC'd Philipp Tomsich who is the co-chair of the RISC-V Software
Standing Committee and Philipp has been helping to coordinate efforts
between Alibaba T-Head, other RVI members and the upstream Linux
maintainers.

Thanks,
Drew

[Gareth Halfacree]

Thanks, Drew, Jeff.

Philipp: do you have anything you can share on the current state of
play regarding mainline support?

Cheers,

-Gareth

On Tue, 2 Nov 2021 at 19:42, Jeff Scheel <je...@riscv.org> wrote:
>
> Gareth, Drew is correct. Philipp is helping ensure that RISC-V has both a good technical path forward and consistent message. So, please reach out to him directly and keep me in the loop so that I can help facilitate any person-to-person chat needed. Sound ok?
> -Jeff
>
> --
> Jeff Scheel (he/him/his)
> Linux Foundation, RISC-V Technical Program Manager

[Hauke Mehrtens]

Some people from the sunxi community are working on upstreaming, but I
do not know what is the progress there:
https://linux-sunxi.org/Allwinner_Nezha

Hauke

[Gabe R]

From what I can tell, the main effort for mainlining support for u-boot, openSBI, and the Linux kernel is being run by Fu Wei (aka tekkamanninja on github), as shown herehttps://fedoraproject.org/wiki/Architectures/RISC-V/Allwinner#Tekkaman_REPOs_for_Fedora_Image. But there is almost no information regarding what has been done, and what still needs to be done.

Looking through the members of this board, it seems that he is a member of this group, so I added him to my list of people I am replying to here.

I know next to nothing about u-boot and Linux kernel development, but I would love to learn and help out in any way possible if we could get some more info about what still needs to be do.

Gabe R

[Robert Lipe]

I'm not sure if these slides existed when Drew spoke earlier in this thread, and some of the prologue will certainly be familiar to this group, but https://tinyurl.com/pdxlug-riscv can help answer some of the very literal questions asked that sparked this thread. 

There is seemingly some unresolved snippiness between the People Making The Chips/Boards, The People Making The Spec, and The People Doing The Work - duly noting that any given human can be in zero or more of those groups. You can see that starting around msg 127 at https://lists.riscv.org/g/software/topic/agenda_for_the_software_hc/85932857 It looks like there are currently many underfunded projects that need developers.

For example, it looks like development work in QEmu/Spike/Renode on the new extensions, particularly, may have a nice multiplier on unlocking other developers because in many of these cases, boards implementing new specs can still be distant. Emulators->Tools->OSes->Apps. There seems to be a pretty wide gamut of work to be done and even whittling down the list of open tasks to write good "help wanted" notes for the various projects is a pretty big gask of its own.

https://wiki.riscv.org/display/TECH/RISC-V+extension+and+feature+support+in+the+Open+Source+SW+Ecosystem also just got a batch of updates a few days ago.

All opinions and interpretations are mine. They may be wrong. 

RJL

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