Re: [PATCH v4 10/12] qtest/qmp-cmd-test: Make test build-independent from accelerator

From: Markus Armbruster <armbru@redhat.com>
To: "Philippe Mathieu-Daudé" <philmd@redhat.com>
Cc: "Laurent Vivier" <lvivier@redhat.com>,
	"Peter Maydell" <peter.maydell@linaro.org>,
	"Thomas Huth" <thuth@redhat.com>,
	"Daniel P.Berrangé" <berrange@redhat.com>,
	"Eduardo Habkost" <ehabkost@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	"Juan Quintela" <quintela@redhat.com>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"Andrew Jones" <drjones@redhat.com>,
	qemu-devel@nongnu.org, qemu-arm@nongnu.org,
	"Claudio Fontana" <cfontana@suse.de>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Igor Mammedov" <imammedo@redhat.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH v4 10/12] qtest/qmp-cmd-test: Make test build-independent from accelerator
Date: Thu, 29 Apr 2021 15:22:43 +0200	[thread overview]
Message-ID: <874kfprzrw.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <1de6b3f8-7d7c-9280-4cd3-633a19dd9b8e@redhat.com> ("Philippe =?utf-8?Q?Mathieu-Daud=C3=A9=22's?= message of "Thu, 29 Apr 2021 10:41:34 +0200")

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

> On 4/29/21 7:43 AM, Markus Armbruster wrote:
>> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
>> 
>>> Now than we can probe if the TCG accelerator is available
>>> at runtime with a QMP command, do it once at the beginning
>>> and only register the tests we can run.
>>> We can then replace the #ifdef'ry by a runtime check.
>>>
>>> Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> 
>> Please read the last remark first.  The other ones are detail; feel free
>> to skip them until we're done with the last one.
>> 
>>> ---
>>>  tests/qtest/qmp-cmd-test.c | 18 ++++++++++++++----
>>>  1 file changed, 14 insertions(+), 4 deletions(-)
>
>>> +    tcg_accel_available = qtest_has_accel("tcg");
>>> +
>> 
>> When does tcg_accel_available differ from defined(CONFIG_TCG)?
>
> qtest_has_accel("tcg") is a runtime check, while defined(CONFIG_TCG)
> is build-time.

Let me rephrase my question: under what conditions can the values of
qtest_has_accel("tcg") and defined(CONFIG_TCG) differ?

> Having tests doing runtime checking allow to:
>
> - have easier reviews, having less #ifdef'ry
> - build them once for all targets
> - build them once for all ./configure options
>   (thinking about CI, the a single job could build the tests, then
>   we run them using the QEMU binaries from other jobs)
> - use the same binaries to test the built binary and the distribution
>   installed one
> - remove the dependencies between tests and binaries
>
>> 
>>>      g_test_init(&argc, &argv, NULL);
>>>  
>>>      qmp_schema_init(&schema);
>> 