From: Philippe Mathieu-Daudé <philmd@redhat.com>

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.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Suggested-by: Daniel Berrangé <berrange@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20210125144530.2837481-5-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 meson.build | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/meson.build b/meson.build
index 3a13ba3307..4cc3ebb827 100644
--- a/meson.build
+++ b/meson.build
@@ -231,6 +231,13 @@ if not get_option('tcg').disabled()
     else
       error('Unsupported CPU @0@, try --enable-tcg-interpreter'.format(cpu))
     endif
+  elif get_option('tcg_interpreter')
+    warning('Use of the TCG interpretor is not recommended on this host')
+    warning('architecture. There is a native TCG execution backend available')
+    warning('which provides substantially better performance and reliability.')
+    warning('It is strongly recommended to remove the --enable-tcg-interpreter')
+    warning('configuration option on this architecture to use the native')
+    warning('backend.')
   endif
   if get_option('tcg_interpreter')
     tcg_arch = 'tci'
-- 
2.29.2

On Mon, 8 Feb 2021 at 23:09, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> From: Philippe Mathieu-Daudé <philmd@redhat.com>
>
> 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.
>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Suggested-by: Daniel Berrangé <berrange@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
> Message-Id: <20210125144530.2837481-5-philmd@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  meson.build | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/meson.build b/meson.build
> index 3a13ba3307..4cc3ebb827 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -231,6 +231,13 @@ if not get_option('tcg').disabled()
>      else
>        error('Unsupported CPU @0@, try --enable-tcg-interpreter'.format(cpu))
>      endif
> +  elif get_option('tcg_interpreter')
> +    warning('Use of the TCG interpretor is not recommended on this host')
> +    warning('architecture. There is a native TCG execution backend available')
> +    warning('which provides substantially better performance and reliability.')
> +    warning('It is strongly recommended to remove the --enable-tcg-interpreter')
> +    warning('configuration option on this architecture to use the native')
> +    warning('backend.')
>    endif
>    if get_option('tcg_interpreter')

Just noticed this one after it hit master, but there's a typo here:
"TCG interpretor" should be "interpreter".

thanks
-- PMM