From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:34482 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757838AbcK3S2n (ORCPT ); Wed, 30 Nov 2016 13:28:43 -0500 Message-ID: <583F1A5A.7040708@redhat.com> Date: Wed, 30 Nov 2016 13:28:42 -0500 From: Prarit Bhargava MIME-Version: 1.0 Subject: Re: Odd build breakage in 4.9-rc7 References: <20161130172435.GG8563@redhat.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Linus Torvalds , Jarod Wilson Cc: Linux Kernel Mailing List , Tony Luck , zarniwhoop73@googlemail.com, linux-kbuild@vger.kernel.org On 11/30/2016 01:18 PM, Linus Torvalds wrote: > On Wed, Nov 30, 2016 at 9:24 AM, Jarod Wilson wrote: >> >> Now, if I omit the -j8 and do a single-threaded build, then things work >> fine. Prarit bisected this failure to commit >> 9a6fb28a355d2609ace4dab4e6425442c647894d, and indeed, when reverting that >> patch and the two that follow it from rc7, parallel make works again. > > I seriously doubt that commit really makes a difference, and I think > it was just random luck. > > Do you perhaps have ccache installed? > > Because ccache at some point broke dependency generation of "gcc -MM" > that the kernel build system uses, giving those random "No such file" > build errors. > > Try uninstalling ccache and see if that helps. > I reported this last week on LKML and I'm building on a freshly installed systems that do not have ccache installed. For example, [root@intel-brickland-04 linux]# rpm -q ccache package ccache is not installed [root@intel-brickland-04 linux]# which ccache /usr/bin/which: no ccache in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/usr/libexec/git-core:/root/bin) In my case I tracked this to commit 3637efb00864 ("x86/mce: Add PCI quirks to identify Xeons with machine check recovery") which adds the include for generated/autoksyms.h. Searching LKML and I came across a report from Ken Moffat from a month ago: http://marc.info/?l=linux-kernel&m=147794681124332&w=2 Also cc'ing linux-kbuild. P. > Linus >