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From: "Daniel P. Berrangé" <berrange@redhat.com>
To: "Philippe Mathieu-Daudé" <philmd@redhat.com>
Cc: Stefan Weil <sw@weilnetz.de>, Thomas Huth <thuth@redhat.com>,
	Richard Henderson <richard.henderson@linaro.org>,
	qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v3 2/4] meson: Warn when TCI is selected but TCG backend is available
Date: Mon, 25 Jan 2021 09:50:49 +0000	[thread overview]
Message-ID: <20210125095049.GC3527172@redhat.com> (raw)
In-Reply-To: <20210122133004.1913923-3-philmd@redhat.com>

On Fri, Jan 22, 2021 at 02:30:02PM +0100, 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.
> 
> Reviewed-by: Stefan Weil <sw@weilnetz.de>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> 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 d5b76150e49..d3df5fa3516 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

warning('Use of the TCG interpretor is not recommended on this host
         architecture. There is a native TCG execution backend available
         which provides substantially better performance and reliability. 
         It is strongly recommended to remove the --enable-tcg-interpreter 
         configuration option on this architecture to use the native
	 backend.')


Regards,
Daniel
-- 
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  reply	other threads:[~2021-01-25  9:53 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-22 13:30 [PATCH v3 0/4] meson: Try to clarify TCG / TCI options for new users Philippe Mathieu-Daudé
2021-01-22 13:30 ` [PATCH v3 1/4] meson: Explicit TCG backend used Philippe Mathieu-Daudé
2021-01-22 13:30 ` [PATCH v3 2/4] meson: Warn when TCI is selected but TCG backend is available Philippe Mathieu-Daudé
2021-01-25  9:50   ` Daniel P. Berrangé [this message]
2021-01-22 13:30 ` [PATCH v3 3/4] configure: Improve TCI feature description Philippe Mathieu-Daudé
2021-01-22 13:30 ` [PATCH v3 4/4] configure: Reword --enable-tcg-interpreter as --disable-native-tcg Philippe Mathieu-Daudé
2021-01-23 18:13   ` Paolo Bonzini
2021-01-24 15:49     ` Philippe Mathieu-Daudé
2021-01-23 18:13 ` [PATCH v3 0/4] meson: Try to clarify TCG / TCI options for new users Paolo Bonzini

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