Re: [PATCH v1 5/6] riscv/virt: Add the PFlash CFI01 device

[Alistair Francis]

On Wed, Sep 25, 2019 at 2:00 AM Markus Armbruster <address@hidden> wrote:
>
> Alistair Francis <address@hidden> writes:
>
> > On Mon, Sep 23, 2019 at 2:46 PM Peter Maydell <address@hidden> wrote:
> >>
> >> On Fri, 20 Sep 2019 at 23:23, Alistair Francis <address@hidden> wrote:
> >> > On Thu, Sep 19, 2019 at 10:15 PM Bin Meng <address@hidden> wrote:
> >> > > I don't think we should mirror what is used on ARM virt board to
> >> > > create 2 flash for sifive_u. For ARM virt, there are 2 flashes because
> >> > > they need distinguish secure and non-secure. For sifive_u, only one is
> >> > > enough.
> >> >
> >> > I went back and forward about 1 or 2. Two seems more usable as maybe
> >> > someone wants to include two pflash files? The Xilinx machine also has
> >> > two so I'm kind of used to 2, but I'm not really fussed.
> >>
> >> One of the reasons for having 2 on the Arm board (we do this
> >> even if we're not supporting secure vs non-secure) is that
> >> then you can use one for a fixed read-only BIOS image (backed
> >> by a file on the host filesystem shared between all VMs), and
> >> one backed by a read-write per-VM file providing permanent
> >> storage for BIOS environment variables. Notably UEFI likes to
> >> work this way, but the idea applies in theory to other
> >> boot loader or BIOSes I guess.
> >
> > This seems like a good reason to have two and there isn't really a
> > disadvantage so I have kept it with two.
>
> Good.
>
> Implementing sector locking would be even better.  I'm not asking you to
> do that work.
>
> >> I would suggest also checking with Markus that your code
> >> for instantiating the flash devices follows the current
> >> recommendations so the backing storage can be configured
> >> via -blockdev. (This is a fairly recent change from June or
> >> so; current-in-master virt and sbsa boards provide an example
> >> of doing the right thing, I think.)
> >
> > I have updated the code to more closely match the ARM virt machine, so
> > I think I'm doing it correctly.
>
> You might want to consider omitting legacy configuration options -drive
> if=pflash and -bios for a simpler interface.

We just moved to -bios and it's been really helpful.

Doesn't -pflash use -drive if=pflash? How else should these be attached?

Alistair