From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5FC5FC4321E for ; Fri, 7 Sep 2018 21:00:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 05C8D2075B for ; Fri, 7 Sep 2018 21:00:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 05C8D2075B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727991AbeIHBnK (ORCPT ); Fri, 7 Sep 2018 21:43:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:39336 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727488AbeIHBmP (ORCPT ); Fri, 7 Sep 2018 21:42:15 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6DF842087C; Fri, 7 Sep 2018 20:59:33 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.91) (envelope-from ) id 1fyNqm-0001r3-FZ; Fri, 07 Sep 2018 16:59:32 -0400 Message-Id: <20180907205932.386725513@goodmis.org> User-Agent: quilt/0.65 Date: Fri, 07 Sep 2018 16:59:13 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-rt-users Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , Julia Cartwright , Daniel Wagner , tom.zanussi@linux.intel.com Subject: [PATCH RT 16/24] efi: Disable runtime services on RT References: <20180907205857.262840394@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14.63-rt41-rc2 stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior [ Upstream commit 55544e1d5eb0d7608e2b41452729649c8ea1607a ] Based on meassurements the EFI functions get_variable / get_next_variable take up to 2us which looks okay. The functions get_time, set_time take around 10ms. Those 10ms are too much. Even one ms would be too much. Ard mentioned that SetVariable might even trigger larger latencies if the firware will erase flash blocks on NOR. The time-functions are used by efi-rtc and can be triggered during runtimed (either via explicit read/write or ntp sync). The variable write could be used by pstore. These functions can be disabled without much of a loss. The poweroff / reboot hooks may be provided by PSCI. Disable EFI's runtime wrappers. This was observed on "EFI v2.60 by SoftIron Overdrive 1000". Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Steven Rostedt (VMware) --- drivers/firmware/efi/efi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 9bd749389f31..47093745a53c 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -74,7 +74,7 @@ static unsigned long *efi_tables[] = { &efi.mem_attr_table, }; -static bool disable_runtime; +static bool disable_runtime = IS_ENABLED(CONFIG_PREEMPT_RT_BASE); static int __init setup_noefi(char *arg) { disable_runtime = true; -- 2.18.0