Re: [PATCH V2 0/2] Proposing custom CSR handling logic

[Alistair Francis <alistair23@gmail.com>]

On Thu, May 13, 2021 at 12:47 AM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> On Wed, May 12, 2021 at 2:03 PM Alistair Francis <alistair23@gmail.com> wrote:
> >
> > On Tue, May 11, 2021 at 8:07 PM Ruinland Chuan-Tzu Tsai
> > <ruinland@andestech.com> wrote:
> > >
> > > Hi all,
> > >
> > > My sincere apology that I missed the patch to include our own CSR table
> > > into the patch series and there were plenty of typos.
> > > Thus I'm sending out V2 of these tiny patches.
> > >
> > > I agree with Alistair's comment on not introducing intrusive code which
> > > will interfere the generic code structure. Yet since there are
> > > possibilities that some custom CSRs/instructions could be once drafted/
> > > proposed by vendors at first, and made themselves into the standard
> > > as the implementation become widely adopted.
> > >
> > > So in this patch set, we humbly utilzed a glib hash table for inserting
> > > the `struct riscv_custom_csr_operations`, check if the CSR is a non
> > > standard one, and then proceed the desired behavior.
> > >
> > > Once the non-standard CSRs make themselves into the specification,
> > > people could easily plug-and-use the code into CSR operation table
> > > inside `csr.c`.
> > >
> > > Ones may have concerns regarding the check code would introduce
> > > further overhead. For those considerations, I guess it could be solved
> > > by introducing a build option such as '--enable-riscv-vendor-features'
> > > to toggle the code.
> > >
> > > Cordially yours,
> > > Ruinland ChuanTzu Tsai
> > >
> > > Ruinland Chuan-Tzu Tsai (2):
> > >   Adding premliminary support for custom CSR handling mechanism
> > >   Adding custom Andes CSR table.
> >
> > Thanks for the patches.
> >
> > Can you please include:
> >  wangjunqiang@iscas.ac.cn
> >  qemu-devel@nongnu.org
> >  bin.meng@windriver.com
> >
> > on future patches so everyone is included.
>
> Thanks Alistair!
>
> >
> > >
> > >  target/riscv/cpu.c           |  28 ++++++++
> > >  target/riscv/cpu.h           |  12 +++-
> > >  target/riscv/cpu_bits.h      | 115 ++++++++++++++++++++++++++++++++
> > >  target/riscv/csr.c           | 107 ++++++++++++++++++++++++++++--
> > >  target/riscv/csr_andes.inc.c | 125 +++++++++++++++++++++++++++++++++++
> > >  5 files changed, 381 insertions(+), 6 deletions(-)
>
> I didn't see the original patch set in the ML, nor does it show up on
> patchwork. I wonder is it posted on the ML?

It might not have. It is an early version and needs some more work,
but it does seem to be on the right track. I left a few comments but
hopefully the next version will make it to the mailing list.

I will CC you on the response so you can see.

Alistair

>
> Regards,
> Bin