Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751297AbaB1GM7 (ORCPT ); Fri, 28 Feb 2014 01:12:59 -0500 Received: from cavan.codon.org.uk ([93.93.128.6]:40673 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750740AbaB1GM6 (ORCPT ); Fri, 28 Feb 2014 01:12:58 -0500 Date: Fri, 28 Feb 2014 06:12:54 +0000 From: Matthew Garrett To: "Li, Aubrey" Cc: "alan@linux.intel.com" , linux-kernel@vger.kernel.org, "H. Peter Anvin" , Len.Brown@intel.com, Adam Williamson Subject: Re: [patch] x86: Introduce BOOT_EFI and BOOT_CF9 into the reboot sequence loop Message-ID: <20140228061254.GA2226@srcf.ucam.org> References: <53100C8D.1060001@linux.intel.com> <20140228045637.GA28257@srcf.ucam.org> <53101D1D.9010202@linux.intel.com> <20140228055629.GA847@srcf.ucam.org> <531027BE.2010807@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <531027BE.2010807@linux.intel.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@cavan.codon.org.uk X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 28, 2014 at 02:07:58PM +0800, Li, Aubrey wrote: > On 2014/2/28 13:56, Matthew Garrett wrote: > > Probably, once we've got those patches landed (I've lost track of > > whether they're in 3.13 or aimed at 3.14) > > You didn't look the reference I quoted in the patch. > > It's stable if 32/64 bit linux call the corresponding 32/64bit EFI > runtime service. Matt Fleming's mixed mode is aiming at 3.15: > > http://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/log/?h=mixed-mode It's stable as long as you have the 1:1 mapping patches, which are different to the mixed mode patches. Otherwise it'll work on some hardware and crash on others. > > Mm. Not all x86 platforms support cf8/cf9 (Moorestown, for instance) and > > so it's theoretically possible that they'd put some different hardware > > there instead. But then, Moorestown probably has its own reboot code, so > > that may not matter? > > Yes, Moorestown has its own machine_ops. Instead of the system hanging > after issue "reboot" command, I think and suggest CF9 is worth to have a > try. Writing to arbitrary register addresses isn't a good plan if we're on a platform that might have different hardware there. > >> Reset register address: 0xCF9 > >> Value to cause reset: 0x6 > > > > Huh. But that's almost exactly what the PCI reboot code would do. Why > > does the PCI method work but the ACPI one fail? Does it really depend on > > ORing the original value with the reset value? Or is the timing just > > somehow marginal? > > reboot returns at: > > if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER)) > return; > > This is a ACPI bug or intention, who knows. Well, how about we figure that out? Is there a full acpi dump of one of these machines somewhere? -- Matthew Garrett | mjg59@srcf.ucam.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/