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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id y9sm95045206wrn.18.2019.04.17.12.17.04 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 17 Apr 2019 12:17:05 -0700 (PDT) Date: Wed, 17 Apr 2019 21:17:02 +0200 From: Ingo Molnar To: Ard Biesheuvel Cc: "Prakhya, Sai Praneeth" , "H. Peter Anvin" , Daniel Drake , Peter Zijlstra , Borislav Petkov , Thomas Gleixner , Linux Kernel , Linus Torvalds , Jian-Hong Pan , Matt Fleming , linux-efi , "Brown, Len" , "linux-tip-commits@vger.kernel.org" , Endless Linux Upstreaming Team Subject: Re: EFI reboot vs. ACPI reboot (was: Re: [tip:x86/urgent] x86/reboot, efi: Use EFI reboot for Acer TravelMate X514-51T) Message-ID: <20190417191702.GA29062@gmail.com> References: <20190416082042.GA69717@gmail.com> <20190417061650.GA31060@gmail.com> <17516564-37AC-4F77-9C0D-0DD71F8045EA@zytor.com> <20190417182341.GA5140@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Ard Biesheuvel wrote: > On Wed, 17 Apr 2019 at 11:23, Ingo Molnar wrote: > > > > > > * Prakhya, Sai Praneeth wrote: > > > > > I will ask around internally to check if it is a good idea to make EFI > > > reboot the default method when the machine is booted in EFI mode. > > > > Or whether there's some robust signature that indicates "modern EFI > > system where EFI reboot is the primary method"? > > > > Major EFI version or ACPI version or such? > > > > I am actually at Microsoft right now, and I managed to get > clarification on how Windows deals with this: Windows will attempt to > use ACPI reboot first, and will only attempt to use anything else if > that fails. EFI reset is actually its least preferred option, and so > it is highly likely that it is untested on most of the shipping x86 > hardware if any of the other methods work. > > So let's not touch this. Agreed and that's really useful information, thanks! Ingo