From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59022) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dNyRu-0003tC-Dn for qemu-devel@nongnu.org; Thu, 22 Jun 2017 05:30:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dNyRr-0005Uh-A4 for qemu-devel@nongnu.org; Thu, 22 Jun 2017 05:30:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55356) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dNyRr-0005UB-2t for qemu-devel@nongnu.org; Thu, 22 Jun 2017 05:30:47 -0400 References: <1498040401-16361-1-git-send-email-yang.zhong@intel.com> <1498040401-16361-2-git-send-email-yang.zhong@intel.com> <2c901b45-afb8-d807-19e9-14befbfdc3fd@redhat.com> <1082632418.11149315.1498112575500.JavaMail.zimbra@redhat.com> <666c9b73-843f-3669-fe1d-69b5082b2757@redhat.com> <8515dc9c-f632-cefa-fdf2-9fcbc8f962de@redhat.com> From: Thomas Huth Message-ID: Date: Thu, 22 Jun 2017 11:30:43 +0200 MIME-Version: 1.0 In-Reply-To: <8515dc9c-f632-cefa-fdf2-9fcbc8f962de@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 01/15] configure: add the disable-tcg option List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Yang Zhong , anthony xu , qemu-devel@nongnu.org, a rigo On 22.06.2017 11:26, Paolo Bonzini wrote: > > > On 22/06/2017 08:33, Thomas Huth wrote: >> On 22.06.2017 08:22, Paolo Bonzini wrote: >>> >>>> On 21.06.2017 12:19, Yang Zhong wrote: >>>>> Add the disable-tcg option into configure and echo CONFIG_TCG=y into >>>>> $config_target_mak. The default tcg is enabled for all build. If tcg >>>>> is disabled in the build, only i386|x86_64 softmmu option can be disabled, >>>>> other softmmu of tagets and users build defaultly enabled the tcg. >>>> Why do you want to limit this disablement to x86 only? There are also >>>> other architectures that support KVM (ARM, PPC, MIPS), so disabling TCG >>>> might be possible there, too. So I think it might be better to check >>>> whether KVM is possible instead. >>> >>> You need to be careful and not use any helper from e.g. KVM or migration >>> code. So I would be very surprised if any other architecture compiles >>> with --disable-tcg. >> >> OK, fair, but we finally might want to get there, so I think we should >> allow the parameter in the configure script for other architectures, >> too, and then fix the bugs once we can try it out. > > I think it's the other way round---when someone wants to fix it, they > should add their architecture to the list of targets that support > --disable-tcg. "./configure ", as a goal, should fail > immediately if make won't succeed; compilation errors are always a worse > experience. Fine for me, too, but then the configure script should exit with a proper error message when the user tried to specify --disable-tcg on a non-x86 architecture. If I get the current patch right, it silently falls back to CONFIG_TCG=y instead, which is IMHO also a bad experience. Thomas