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 6F2CCC282DA for ; Wed, 17 Apr 2019 16:52:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 405FD217FA for ; Wed, 17 Apr 2019 16:52:18 +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="jAuTWFNX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732919AbfDQQwR (ORCPT ); Wed, 17 Apr 2019 12:52:17 -0400 Received: from terminus.zytor.com ([198.137.202.136]:54473 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731745AbfDQQwQ (ORCPT ); Wed, 17 Apr 2019 12:52:16 -0400 Received: from [IPv6:2607:fb90:8673:1b5f:28a1:6df5:3434:e270] ([IPv6:2607:fb90:8673:1b5f:28a1:6df5:3434:e270]) (authenticated bits=0) by mail.zytor.com (8.15.2/8.15.2) with ESMTPSA id x3HGpo153988963 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO); Wed, 17 Apr 2019 09:51:51 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com x3HGpo153988963 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2019041743; t=1555519912; bh=3FCbNtlpNkBp1GIaA1U+jCEm6STOsOg2M4zm/VQg17I=; h=Date:In-Reply-To:References:Subject:To:CC:From:From; b=jAuTWFNXsXx5elHqDEu9dq3B8vUQKCD1frNZCzgFZW1+aUur2JX8Y+zoKdmjuldm9 etnYCNvqcme2RfAdXyWSzjf2Rt7pgjfdDTX0kDi/0jFr4sXx5oSNAQhKxo1ecqI6Ke LVSwwAYKiYEEgi+GvicD4M7XfWUp6iX3Sd3Q1n9TucrcyotJWtELnwn8956hZbVf5x pODRx2XFyB1YpBB09xRVcJomEu0Ilcs/pLZEQVYDWh5ibLNDrv+4zKFRtkazjUsAzd IWv/n1c2Ig4FciJpbgOJN9A7YFD+na1An8wPQX2U7moNMvw5JqTqyTbkrHQNWu/ZOO qVf7tGUDQNwlQ== Date: Wed, 17 Apr 2019 09:51:47 -0700 User-Agent: K-9 Mail for Android In-Reply-To: <20190417163729.GA53511@gmail.com> References: <20190412080152.3718-1-jian-hong@endlessm.com> <20190416082042.GA69717@gmail.com> <20190417061650.GA31060@gmail.com> <17516564-37AC-4F77-9C0D-0DD71F8045EA@zytor.com> <20190417163729.GA53511@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: Ingo Molnar CC: Daniel Drake , 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: <1DE9F317-8B95-40F4-89AF-A3573B1C4881@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 9:37:29 AM PDT, Ingo Molnar wrote: > >* hpa@zytor=2Ecom wrote: > >> > 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 > >No, I still think "early" EFI is historically better with ACPI reboot=2E > >But can we find a firmware flag perhaps that will *not* result in EFI=20 >reboot being turned off? > >> This, I believe, is known to not work=2E > >Yeah, I bet so=2E > >My problem is that the code appears to have the wrong assumptions: > > /* >* For most modern platforms the preferred method of powering off is via > * ACPI=2E However, there are some that are known to require the use of > * EFI runtime services and for which ACPI does not work at all=2E > * > * Using EFI is a last resort, to be used only if no other option > * exists=2E > */ > bool efi_reboot_required(void) > { > if (!acpi_gbl_reduced_hardware) > return false; > > efi_reboot_quirk_mode =3D EFI_RESET_WARM; > return true; > } > > >At minimum the comment is stale: "modern" platforms, *especially* when=20 >the only bootup method is EFI, as in the ACER laptop case, I think the=20 >preferred reboot method is absolutely an EFI reboot - and it's probably > >what Windows uses too=2E > >The question is, is acpi_gbl_reduced_hardware false on the Acer=20 >TravelMate X514-51T? I think it has to be, for the quirk to make sense >-=20 >if it's true then efi_reboot_required() would set the reboot method to=20 >EFI=2E > >I=2Ee=2E we seem to have a new category of systems that are advertising= =20 >themselves as 'full ACPI compliant', which are NOT old EFI systems, but > >modern EFI systems=2E > >Is there some good way to detect these - such as ACPI version or=20 >something? > >Thanks, > > Ingo That is exactly what the reduced hardware flag is supposed to indicate=2E = As far as what Windows does, the are only two ways to find out: testing som= ehow, or these days Microsoft might actually answer if we ask nicely=2E --=20 Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E