From owner-freebsd-arm@freebsd.org Thu Sep 10 13:30:34 2015 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id BD453A00D8B for ; Thu, 10 Sep 2015 13:30:34 +0000 (UTC) (envelope-from prvs=688ac6705=Ian.Campbell@citrix.com) Received: from SMTP02.CITRIX.COM (smtp02.citrix.com [66.165.176.63]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "mail.citrix.com", Issuer "Verizon Public SureServer CA G14-SHA2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id BBABC1BCD for ; Thu, 10 Sep 2015 13:30:33 +0000 (UTC) (envelope-from prvs=688ac6705=Ian.Campbell@citrix.com) X-IronPort-AV: E=Sophos;i="5.17,504,1437436800"; d="scan'208";a="302696803" Message-ID: <1441891830.24450.384.camel@citrix.com> Subject: Re: [Xen-devel] [PATCH] efi/libstub/fdt: Standardize the names of EFI stub parameters From: Ian Campbell To: Jan Beulich CC: Mark Rutland , "julien.grall@citrix.com" , Stefano Stabellini , "freebsd-arm@freebsd.org" , "peter.huangpeng@huawei.com" , Shannon Zhao , "matt.fleming@intel.com" , "ard.biesheuvel@linaro.org" , "christoffer.dall@linaro.org" , "leif.lindholm@linaro.org" , "shannon.zhao@linaro.org" , "linux-arm-kernel@lists.infradead.org" , "xen-devel@lists.xen.org" , "daniel.kiper@oracle.com" , "devicetree@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-efi@vger.kernel.org" , "linux-kernel@vger.kernel.org" Date: Thu, 10 Sep 2015 14:30:30 +0100 In-Reply-To: <55F19D0202000078000A1B54@prv-mh.provo.novell.com> References: <1441874516-11364-1-git-send-email-zhaoshenglong@huawei.com> <20150910095208.GA29293@leverpostej> <20150910112418.GC29293@leverpostej> <20150910121514.GE29293@leverpostej> <1441889905.24450.382.camel@citrix.com> <55F19D0202000078000A1B54@prv-mh.provo.novell.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5-1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-DLP: MIA1 X-Mailman-Approved-At: Thu, 10 Sep 2015 17:20:03 +0000 X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Sep 2015 13:30:34 -0000 On Thu, 2015-09-10 at 07:08 -0600, Jan Beulich wrote: > > > > On 10.09.15 at 14:58, wrote: > > On Thu, 2015-09-10 at 13:15 +0100, Mark Rutland wrote: > > > > > > In any case this should be separate from the shim ABI discussion. > > > > > > I disagree; I think this is very much relevant to the ABI discussion. > > > That's not to say that I insist on a particular approach, but I think > > > that they need to be considered together. > > > > Taking a step back, the reason for using the EFI stub parameters is > > only > > (AFAIK) in order to be able to locate the ACPI RDSP (the root table > > pointer), which as it happens is normally passed via one of the EFI > > firmware tables. > > > > If there was a way to achieve that goal (i.e. another way to find the > > RSDP) > > without opening the can of UEFI worms then we could consider that > > opiton > > too. > > > > a way != the legacy x86 thing of scanning low memory of the signature, > > of > > course. > > But even x86 doesn't do that (other than as a fallback) on EFI. Indeed, I was referring legacy (non-EFI) mode. > The > configuration table is available to Dom0 (via XENPF_firmware_info: > XEN_FW_EFI_INFO:XEN_FW_EFI_CONFIG_TABLE). Under ARM we find out we are running under Xen from the ACPI tables, so there is a chicken and egg situation there. Not insoluble I'm sure, if we want to go down this route. Ian.