RE: [RFC PATCH 1/2] riscv: vendors: andes: Add support to configure the PMA regions

[Biju Das]

Hi Geert,


> Subject: Re: [RFC PATCH 1/2] riscv: vendors: andes: Add support to
> configure the PMA regions
> 
> Hi Biju,
> 
> On Thu, Sep 8, 2022 at 3:01 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> wrote:
> > > Subject: Re: [RFC PATCH 1/2] riscv: vendors: andes: Add support to
> > > configure the PMA regions
> > >
> > > On 08/09/2022 09:39, Biju Das wrote:
> > > > EXTERNAL EMAIL: Do not click links or open attachments unless you
> > > > know the content is safe
> > > >
> > > > Hi Conor, Atish,
> > > >
> > > > What RISC-V devices you have?
> > >
> > > A bunch ;)
> > >
> > > A __couple__ PolarFire SoC boards, HiFive Unleashed, D1 Nezha,
> > > Canaan
> > > k210 MAIX something & the VisionFive.
> >
> > If standard DMA api works without any issue means, on these platforms
> > IO Coherence port is enabled in the hardware. So all peripherals
> > involving DMA work as expected.
> >
> > > > Ours is RISC-V uniprocessor without IO Coherence Port.
> > >
> > > What does "IO Coherence Port" mean? Zicbo*?
> >
> > The HW will provide coherency between CPU and peripheral.
> >
> > If Zibco* is uniprocessor, then highly it may not have IO coherence
> > Port enabled in their design.
> 
> Zicbo* is a set of extensions for the instructions.
> These cannot be retrofitted to existing silicon, but perhaps they can be
> trapped and emulated?

Thanks for clarifying this. I just gone through RISC-V CMOs.
https://github.com/riscv/riscv-CMOs/blob/master/specifications/cmobase-v1.0.1.pdf

Cheers,
Biju