Re: [PATCH 2/2] meson: Warn when TCI is selected but TCG backend is available

[Thomas Huth]

On 22/01/2021 10.46, Philippe Mathieu-Daudé wrote:
> On Fri, Jan 22, 2021 at 10:43 AM Thomas Huth <thuth@redhat.com> wrote:
> > On 22/01/2021 10.22, Philippe Mathieu-Daudé wrote:
> > > Some new users get confused with 'TCG' and 'TCI', and enable TCI
> > > support expecting to enable TCG.
> > >
> > > Emit a warning when native TCG backend is available on the
> > > host architecture, mentioning this is a suboptimal configuration.
> > >
> > > Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> > > ---
> > >    meson.build | 3 +++
> > >    1 file changed, 3 insertions(+)
> > >
> > > diff --git a/meson.build b/meson.build
> > > index 0a645e54662..7aa52d306c6 100644
> > > --- a/meson.build
> > > +++ b/meson.build
> > > @@ -234,6 +234,9 @@
> > >          error('Unsupported CPU @0@, try --enable-tcg-interpreter'.format(cpu))
> > >        endif
> > >      endif
> > > +  if 'CONFIG_TCG_INTERPRETER' in config_host and cpu in supported_cpus
> > > +    warning('Experimental TCI requested while native TCG is available on @0@, 
> > > suboptimal performance expected'.format(cpu))
> > > +  endif
> > >      accelerators += 'CONFIG_TCG'
> > >      config_host += { 'CONFIG_TCG': 'y' }
> > >    endif
> >
> > Reviewed-by: Thomas Huth <thuth@redhat.com>
> >
> > ... maybe you could also add some wording to the help text of the configure
> > script? Or maybe we could simply rename the "--enable-tcg-interpreter"
> > option into "--enable-tci" to avoid confusion with the normal TCG ?
>
> I also thought about renaming as --enable-experimental-tci but then doubt that
> would help, some users just want to enable everything :)

Then we should rename it into --disable-native-tcg ;-)

 Thomas