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=DKIM_INVALID,DKIM_SIGNED, 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 F1010C282DA for ; Wed, 17 Apr 2019 15:16:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE52921773 for ; Wed, 17 Apr 2019 15:16:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="Ny7U4nnY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732641AbfDQPQb (ORCPT ); Wed, 17 Apr 2019 11:16:31 -0400 Received: from terminus.zytor.com ([198.137.202.136]:53053 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729940AbfDQPQa (ORCPT ); Wed, 17 Apr 2019 11:16:30 -0400 Received: from [IPv6:2601:646:8680:2bb1:44b5:416e:6c3:6b62] ([IPv6:2601:646:8680:2bb1:44b5:416e:6c3:6b62]) (authenticated bits=0) by mail.zytor.com (8.15.2/8.15.2) with ESMTPSA id x3HFG3Te3954512 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO); Wed, 17 Apr 2019 08:16:06 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com x3HFG3Te3954512 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2019041743; t=1555514167; bh=+XtVu+cuYYqMVuESz6fvwq8kAr8YsIY/IcDBD8jljvw=; h=Date:In-Reply-To:References:Subject:To:CC:From:From; b=Ny7U4nnYRxxKf+l1ftuCBnQTIfsc6PdWAvz/ePKIsLvex1LasMUKPOuDd9+4zUJkT vsezgiJ5F+wih9z0bLHtFtgbZCMONdZA514Mhx7PBRW8Hlg6oPh61ybBLLNmRU+EHy WyzCBCY/3ToqM12u1zD5Jpqv7QAFTjIFuK/XWWRuQlhtOr0QiN7p3iePuIo85lgidW nAqtvVTS41dbTTA+HgeBvwLrITd7ZRN5MxxtUzJswlQ92UpfLqD+PaKH09LWIxPoC/ jZExddLQsRvXqurTwf2V5JdFBMTUDdoLD3wOllTRuPE34bTUshKhyvMDoBrnjZWoyd Dzi9Md/WVAwEg== Date: Wed, 17 Apr 2019 08:15:55 -0700 User-Agent: K-9 Mail for Android In-Reply-To: References: <20190412080152.3718-1-jian-hong@endlessm.com> <20190416082042.GA69717@gmail.com> <20190417061650.GA31060@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: EFI reboot vs. ACPI reboot (was: Re: [tip:x86/urgent] x86/reboot, efi: Use EFI reboot for Acer TravelMate X514-51T) To: Daniel Drake , Ingo Molnar CC: Peter Zijlstra , Borislav Petkov , Thomas Gleixner , Linux Kernel , Linus Torvalds , Jian-Hong Pan , matt@codeblueprint.co.uk, Ard Biesheuvel , linux-efi@vger.kernel.org, Len Brown , linux-tip-commits@vger.kernel.org, Endless Linux Upstreaming Team From: hpa@zytor.com Message-ID: <17516564-37AC-4F77-9C0D-0DD71F8045EA@zytor.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On April 17, 2019 5:38:41 AM PDT, Daniel Drake wrote= : >On Wed, Apr 17, 2019 at 2:16 PM Ingo Molnar wrote: >> Ok, so acpi_gbl_reduced_hardware is set when the =2E=2E=2E 'reduced >hardware' >> bit is set: >> >> acpi_gbl_reduced_hardware =3D FALSE; >> if (acpi_gbl_FADT=2Eflags & ACPI_FADT_HW_REDUCED) { >> acpi_gbl_reduced_hardware =3D TRUE; >> } >> >> >> which is described as: >> >> #define ACPI_FADT_HW_REDUCED (1<<20) /* 20: [V5] ACPI >hardware is not implemented (ACPI 5=2E0) */ >> >> That seems counter-intuitive to me: if no full ACPI hardware is >> implemented then we should assume reduced ACPI functionality, i=2Ee=2E = if >the >> EFI runtime is otherwise available we should default to it=2E > >It's a bit confusing, but my loose understanding is that previous >versions of the ACPI spec required system implementors to implement >the whole thing; but that's increasingly impractical today, e=2Eg=2E with >ARM systems coming along, which do not gel well with some of the >historical x86-rooted design aspects that spilled over into ACPI=2E The >V5 spec introduces reduced mode as an opt-in new feature, but for >compatibility with pre-V5 implementations it needs to consider "full >hardware" mode as the default=2E > >> Feel free to send a patch that makes EFI reboot the default one under >> these circumstances, > >Just to check, you mean: EFI reboot (and shutdown) become the default >methods when the machine is booted in EFI mode, and EFI stuff has not >been disabled with a kernel parameter? >Even when running in full hardware ACPI mode=2E > >Thanks >Daniel This, I believe, is known to not work=2E --=20 Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E