Re: [PATCH-for-9.1] target/nios2: Remove machines and system emulation

[Thomas Huth]

On 27/03/2024 15.15, Philippe Mathieu-Daudé wrote:
> On 27/3/24 14:19, Thomas Huth wrote:
> > On 27/03/2024 13.45, Philippe Mathieu-Daudé wrote:
> > > On 27/3/24 13:35, Philippe Mathieu-Daudé wrote:
> > > > Remove the Nios II machines and the system emulation code
> > > > (deprecated since v8.2 in commit 9997771bc1 "target/nios2:
> > > > Deprecate the Nios II architecture").
> >
> > Please remind me, why didn't we deprecate the linux-user emulation, too?
>
> Hmm I think we actually did (overall target), since there is
> an issue with signals.

The placement in the deprecated.rst file seems a bit unfortunate in that 
case, since the subchapter is called "System emulator CPUs" ?

Anyway, I just saw your v2, so let's continue discussion there...

> > > > diff --git a/hw/nios2/Kconfig b/hw/nios2/Kconfig
> > > > deleted file mode 100644
> > > > index 4748ae27b6..0000000000
> > > > --- a/hw/nios2/Kconfig
> > > > +++ /dev/null
> > > > @@ -1,13 +0,0 @@
> > > > -config NIOS2_10M50
> > > > -    bool
> > > > -    select NIOS2
> > > > -    select SERIAL
> > > > -    select ALTERA_TIMER
> > >
> > > I forgot to mention I deliberately chose to keep the Altera
> > > timer model in the tree, since it looks like a re-usable
> > > IP component.
> >
> > But if it is not used anymore by any machine, this will happily bitrot, 
> > won't it? I think I'd rather remove it, too ... maybe in a separate patch, 
> > so that in case somebody later needs it again, it can be restored by 
> > simply reverting the patch again.
>
> It is related to dynamic machines, how do we decide what components
> to remove once there? I suppose we'd need to deprecate every single
> component, like ALTERA_TIMER. But we are not yet generating dynamic
> machines, so for now we can consider ALTERA_TIMER part of Nios II
> sysemu removal. I like your idea of removing it as a separate patch.

Even if we switch to dynamic machines one day, the devices still need to be 
somehow used and tested in the CI, e.g. by scripts that assemble a machine 
dynamically. If there's a device that is never used at all, we can also 
simply remove it until someone needs it again, I think.

 Thomas