On Mon, Oct 18, 2021 at 7:37 PM LIU Zhiwei <zhiwei_...@c-sky.com> wrote: > > Hi Alistair, > > Sorry for the send error. And I have a question about this patch set.
Hello Zhiwei, > > Firstly, I totally support the vector v1.0 upstream. Great! > > The concern is how to deal with the v0.7.1 code on QEMU. There are some > products based on the vector v0.7.1, > such as D1 SOC from Allwinner and Xuantie CPU from Alibaba. The Linux > and GCC upstream for D1 is working in progress, > and eventually these projects will support v0.7.1 in some way, probably > as "x-thead-v" (the "thead" stands for Alibaba T-Head). Yep, so QEMU's stance is to only support the latest version of a draft specification. Once a specification moves from draft to frozen we will also only support the frozen spec. I understand that there is hardware with the v0.7.1 of the vector extension. But in QEMU we don't have the resources for RISC-V to maintain multiple sets of draft extensions. Especially the vector extension, which is very different between v0.7.1 and v1.0 (see the 78 patches in this series). I realise this is disappointing for companies and people who have invested in v0.7.1 in QEMU, and I hope it doesn't put anyone off upstream work. Having the v0.7.1 even for a short period of time has been helpful for the vector extension development and related software/tools. > > Maybe we can > > 1. Drop the v0.7.1 support permanently. > > 2. Drop the v0.7.1 temporarily and add it back later. If in the future there is broad community support for v0.7.1 and we can get some more QEMU resources for RISC-V we can re-evaluate v0.7.1 support. But for the time being it will just be dropped. There are a few QEMU releases with v0.7.1 support, so you can use those for development. The v0.7.1 has received a few bug fixes in the upstream code base which will be beneficial for those using it. Sorry about that Alistair > > 3. Do some compatible work for v0.7.1 in the v1.0 patch set. > > Look forward to your idea. Thanks very much. > > Best Regards, > Zhiwei > > On 2021/10/18 下午5:01, LIU Zhiwei wrote: > > Hi Alistair, > > > > There is some products based on the vector v0.7.1, such as D1 SOC from > > Allwinner and Xuantie CPU And we have spent a lot of work to > > support vector on QEMU. > > > > > > > > Allwinner > > > >