Re: [PATCH] riscv: Make semihosting configurable for all privilege modes

[Furquan Shaikh]

On Sun, Aug 14, 2022 at 3:04 PM Alistair Francis <alistair23@gmail.com> wrote:
>
> On Sat, Aug 13, 2022 at 8:20 PM Peter Maydell <peter.maydell@linaro.org> 
> wrote:
> >
> > On Sat, 13 Aug 2022 at 01:53, Furquan Shaikh <furquan@rivosinc.com> wrote:
> > > I ran into a problem when I was testing a project (with a microkernel
> > > in M-mode and tasks in U-mode) that uses semihosting for debugging.
> > > The semihosting worked fine for M-mode but not in U-mode. As I started
> > > digging into this, I realized that this is because qemu restricts
> > > semihosting to only M and S modes.
> >
> > Right. We should fix this by having a generic works-for-all-architectures
> > semihosting config knob, because this is not a riscv specific problem,
> > and we already have issues with different target architectures
> > developing their own solutions to things.
>
> I agree with Peter here. I don't see a strong use case for a RISC-V
> specific fine grained control. A user can either enable/disable
> semihosting for privilege or usermodes (with Peter's patchset). That
> seems like enough configuration options, it is unlikely that someone
> will need semihosting only available to S-mode for example.

Sounds good. Thanks for the feedback. I can continue with the changes
that Peter has.

>
> Alistair
>
> >
> > I'll see if I can dig out the half-done patchset I had for this.

Let me know if you want to collaborate on this to get this to
completion. Thanks!

> >
> > thanks
> > -- PMM
> >