Re: [PATCH v2] hw/riscv: virt: Assume M-mode FW in pflash0 only when "-bios none"

[Andrea Bolognani]

On Thu, May 18, 2023 at 02:53:05PM +1000, Alistair Francis wrote:
> On Wed, May 17, 2023 at 6:45 PM Andrea Bolognani <abologna@redhat.com> wrote:
> > On Wed, May 17, 2023 at 02:57:12PM +1000, Alistair Francis wrote:
> At one point we loaded Oreboot in in flash and booted from that. I
> think Oreboot then loaded OpenSBI into memory. The idea was to mimic
> what a physical board would do, so we could allow testing.
>
> It doesn't look like it's used any more.
>
> > Either way, assuming that there's a genuine reason why pflash must be
> > used, I think the behavior implemented in v1 (pflash0 is M-mode when
> > -bios none is used, S-mode otherwise) maps very well conceptually,
> > and results in behavior matching that of other architectures out of
> > the box. That's good enough for me :) I was just wondering whether we
> > could keep things even simpler.
>
> I don't see a reason to remove the boot from pflash if no -bios
> argument is supplied. If there is a good reason to, I think we can
> (via deprecation) but the current functionality seems fine to me.

Aligning with other architectures.

In the short term, we cause some minor pain to existing users,
although as noted above for the oreboot case there might not even be
any people still depending on this functionality at this point.

In the long run, we guarantee smooth operation across the stack by
not being different for being different's sake (e.g. requiring
pflash0 and pflash1 to be swapped compared to x86 and Arm, which is a
configuration that falls outside what can be described by the
firmware.json standard and thus can't be automatically applied by
libvirt).

-- 
Andrea Bolognani / Red Hat / Virtualization