Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755995AbbBGDgz (ORCPT ); Fri, 6 Feb 2015 22:36:55 -0500 Received: from mail-pa0-f48.google.com ([209.85.220.48]:59004 "EHLO mail-pa0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751421AbbBGDgx (ORCPT ); Fri, 6 Feb 2015 22:36:53 -0500 Message-ID: <54D5884A.6050009@linaro.org> Date: Sat, 07 Feb 2015 11:36:42 +0800 From: Hanjun Guo User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: G Gregory , Mark Rutland , Leif Lindholm CC: Catalin Marinas , "Rafael J. Wysocki" , Olof Johansson , Arnd Bergmann , "grant.likely@linaro.org" , Will Deacon , Lorenzo Pieralisi , Sudeep Holla , "jcm@redhat.com" , Jason Cooper , Marc Zyngier , Bjorn Helgaas , Daniel Lezcano , Mark Brown , Rob Herring , Robert Richter , Randy Dunlap , Charles Garcia-Tobin , "phoenix.liyi@huawei.com" , Timur Tabi , Ashwin Chaugule , "suravee.suthikulpanit@amd.com" , Mark Langsdorf , "wangyijing@huawei.com" , "linux-acpi@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linaro-acpi@lists.linaro.org" , Jonathan Corbet , Matt Fleming Subject: Re: [PATCH v8 08/21] dt / chosen: Add linux,uefi-stub-generated-dtb property References: <1422881149-8177-1-git-send-email-hanjun.guo@linaro.org> <1422881149-8177-9-git-send-email-hanjun.guo@linaro.org> <20150202134033.GR4278@bivouac.eciton.net> <20150202135051.GA3825@xora-haswell.xora.org.uk> <20150202163253.GG21175@leverpostej> In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2528 Lines: 59 On 2015年02月06日 18:34, G Gregory wrote: [...] >>>>> -------------------------------------------------------------------------------- >>>>> linux,uefi-stub-kern-ver | string | Copy of linux_banner from build. >>>>> -------------------------------------------------------------------------------- >>>>> +linux,uefi-stub-generated-dtb | bool | Indication for no DTB provided by >>>>> + | | firmware. >>>>> +-------------------------------------------------------------------------------- >>>> >>>> Apologies for the late bikeshedding, but the discussion on this topic >>>> previsously was lively enough that I thought I'd let it die down a bit >>>> before seeing if I had anything to add. >>>> >>>> That, and I just realised something: >>>> One alternative to this added DT entry is that we could treat the >>>> absence of a registered UEFI configuration table as the indication >>>> that no HW description was provided from firmware, since the stub does >>>> not call InstallConfigurationTable() on the DT it generates. This does >>>> move the ability to detect to after efi_init(), but this should be >>>> fine for ACPI-purposes. >>>> >>> That would not work as expected in the kexec/Xen use case though as they >>> may genuinely boot with DT from an ACPI host without UEFI. >> >> I'm a little concerned by this case. How do we intend to pass stuff from >> Xen to the kernel in this case? When we initially discussed the stub >> prior to merging, we weren't quite sure if ACPI without UEFI was >> entirely safe. >> >> The linux,uefi-stub-kern-ver property was originally intended as a >> sanity-check feature to ensure nothing (including Xen) masqueraded as >> the stub, but for some reason the actual sanity check was never >> implemented. >> >>>> If that is deemed undesirable, I would still prefer Catalin's >>>> suggested name ("linux,bare-dtb"), which describes the state rather >>>> than the route we took to get there. >>>> >>> I agree. >> >> I guess this would be ok, though it would be nice to know which agent >> generated the DTB. >> > > The most obvious scheme then is > > linux,bare-dtb = "uefi-stub"; > > otherwise we generate a new binding for every component in the boot path. Leif, Mark, any comments on this? Thanks Hanjun -- 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/