From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57840) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dQc8Z-00011L-RE for qemu-devel@nongnu.org; Thu, 29 Jun 2017 12:17:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dQc8U-0003s3-6C for qemu-devel@nongnu.org; Thu, 29 Jun 2017 12:17:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39848) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dQc8T-0003qp-Qu for qemu-devel@nongnu.org; Thu, 29 Jun 2017 12:17:42 -0400 References: <20170629010300.2848-1-f4bug@amsat.org> <0e0d7ae6-5c1e-5c54-9d09-ef03e600b87e@redhat.com> <98d49899-a2d8-8ecc-70ac-becc5252ae32@redhat.com> <20170629160749.GH32167@redhat.com> From: Thomas Huth Message-ID: <40abfed5-44fd-fc53-be7b-7836716e7e92@redhat.com> Date: Thu, 29 Jun 2017 18:17:36 +0200 MIME-Version: 1.0 In-Reply-To: <20170629160749.GH32167@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [RFC PATCH 0/8] removal of tci (tcg interpreter) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: Paolo Bonzini , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org, Richard Henderson , =?UTF-8?Q?Alex_Benn=c3=a9e?= , "Emilio G . Cota" , Stefan Weil , Peter Maydell On 29.06.2017 18:07, Daniel P. Berrange wrote: > On Thu, Jun 29, 2017 at 05:46:26PM +0200, Thomas Huth wrote: >> On 29.06.2017 17:06, Paolo Bonzini wrote: >>> >>> >>> On 29/06/2017 10:46, Thomas Huth wrote: >>>>> Patches 7,8 are the removal, marked RFC... let's debate! >>>> ... but NACK for a direct removal. Common sense is to make obsolete >>>> features as deprecated first and then wait for 2 public releases bef= ore >>>> the final removal, so that users still have a chance to speak up in = case >>>> they still need the feature and are willing to maintain it. >>> >>> I think this is a slightly different case than what is in >>> http://wiki.qemu.org/Features/LegacyRemoval. >>> >>> TCI is enabled only with a specific configure argument if your machin= e >>> is not supported by TCG. This would break _build_ configurations, no= t >>> user configurations. It's a remote possibility that users are buildi= ng >>> their own QEMU, with TCI enabled, to work around a TCG bug. So we ca= n >>> be more speedy in removing the code. >> >> You never know ... it's unlikely, but there might be people around who >> run configure with "--enable-tcg-interpreter" on purpose. And why the >> hurry for removing this? It's been around in the current shape since >> years, so waiting for two more releases does not hurt, does it? >=20 > The flipside is that even if we delete it, if someone does suddenly > care, the code is still there in git & easy to undelete again. Given > that we believe there are zero users, it is known broken in many > ways, and TCG provides a working alternative, I don't see a strong > reason to not just kill it right away.=20 At least I was using TCI a couple of times during the last years (when I was suspecting a bug in the normal TCG backend, so I could compare). There might be other people, too, so I would not dare to say that there are zero users! Though I used it a couple of times in the past, I personally would not object the removal of TCI nowadays since the normal TCG backends have become pretty mature ... but other users of TCI might have a different opinion here, so let's mark it as deprecated now and remove it next year (unless somebody speaks up and explains why it should not be removed). Thomas