From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51620) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZrpVy-0003nH-QJ for qemu-devel@nongnu.org; Thu, 29 Oct 2015 11:53:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZrpVw-0006kg-35 for qemu-devel@nongnu.org; Thu, 29 Oct 2015 11:53:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58529) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZrpVv-0006kP-U6 for qemu-devel@nongnu.org; Thu, 29 Oct 2015 11:53:20 -0400 References: <1446055000-29150-1-git-send-email-jsnow@redhat.com> <87611q8agw.fsf@blackfin.pond.sub.org> From: John Snow Message-ID: <563240ED.2080700@redhat.com> Date: Thu, 29 Oct 2015 11:53:17 -0400 MIME-Version: 1.0 In-Reply-To: <87611q8agw.fsf@blackfin.pond.sub.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] configure: disallow ccache during compile tests List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: peter.maydell@linaro.org, qemu-devel@nongnu.org, pbonzini@redhat.com On 10/29/2015 02:17 AM, Markus Armbruster wrote: > John Snow writes: > >> If the user is using CCACHE during the configuration step, >> it may interfere with some of the configuration tests, >> particularly the "Is CCACHE interfering with macro analysis" step, >> which is a bit of a poetic problem. >> >> 1) Disallow CCACHE from reading from the cache during configure, >> but don't disable it to allow us to see if it causes other problems. > > This is confusing. "don't disable it entirely"? > We allow it to submit items into the cache, but not to read items from the cache. This prevents it from picking up cached results to the compile tests. I don't disable it entirely (just pass-through to the real compiler without using ccache at all) because I still want to allow ccache to be processing things to test for ccache failures -- particularly the ccache macro check that occurs later. If I just disable ccache, that later check is meaningless. Setting the cache to "write only" gives me the best of both worlds. >> 2) Force off CCACHE_CPP2 during the ccache test to get a deterministic >> answer over whether or not we need to enable that feature later. >> >> Signed-off-by: John Snow