From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: linux-rt-users-owner@vger.kernel.org Received: from mail.efficios.com ([167.114.142.138]:51152 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730571AbeISC3i (ORCPT ); Tue, 18 Sep 2018 22:29:38 -0400 Date: Tue, 18 Sep 2018 16:55:14 -0400 From: Jonathan Rajotte-Julien Subject: __migrate_disabled symbol not exported for rt kernel > 4.9 Message-ID: <20180918205514.GB31793@joraj-alpa> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-rt-users-owner@vger.kernel.org List-ID: To: bigeasy@linutronix.de Cc: linux-rt-users@vger.kernel.org, skrishnakar@gmail.com Hi, While building/linking our out-of-tree modules, lttng-modules, against 4.14.69-rt43 we encounter this error: WARNING: "__migrate_disabled" [/home/builder/lttng-modules/lttng-modules-2.10.7/lttng-tracer.ko] undefined! Same problem for other stable rt kernels > 4.9. Everything work fine against 4.9.115-rt93. It looks like __migrate_disabled was moved from linux/include/sched.h to linux/include/preempt.h. No problem there but for a configuration the inline function was transformed into a function declaration. The symbol for that function is not currently exported (EXPORT_SYMBOL*). Should __migrate_disabled be exported when defined in kernel/sched/core.c? And for personal knowledge: What is the reason for not using an inline function for the (CONFIG_SMP) && (CONFIG_PREEMPT_RT_BASE) configuration? The commit message introducing __migrate_disabled does not give much information regarding why it is done differently compared to 4.9-rt kernels. We will probably end up accessing the migrate_disabled field directly since we need to support those kernel versions somehow. Cheers -- Jonathan Rajotte-Julien EfficiOS