Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752955Ab3FZTcI (ORCPT ); Wed, 26 Jun 2013 15:32:08 -0400 Received: from mail-we0-f171.google.com ([74.125.82.171]:39508 "EHLO mail-we0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752307Ab3FZTcF (ORCPT ); Wed, 26 Jun 2013 15:32:05 -0400 Date: Wed, 26 Jun 2013 21:31:58 +0200 From: Leif Lindholm To: Stephen Warren Cc: Grant Likely , "linux-arm-kernel@lists.infradead.org" , linux-efi@vger.kernel.org, "linux-doc@vger.kernel.org" , Linux Kernel Mailing List , "patches@linaro.org" , "H. Peter Anvin" , Thomas Gleixner , matt.fleming@intel.com Subject: Re: [PATCH 1/4] Documentation: arm: [U]EFI runtime services Message-ID: <20130626193158.GF9078@rocoto.smurfnet.nu> References: <1372183863-11333-1-git-send-email-leif.lindholm@linaro.org> <1372183863-11333-2-git-send-email-leif.lindholm@linaro.org> <51CA2B03.4080106@wwwdotorg.org> <51CB33BE.2020601@wwwdotorg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <51CB33BE.2020601@wwwdotorg.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1963 Lines: 40 On Wed, Jun 26, 2013 at 12:32:30PM -0600, Stephen Warren wrote: > >> What about ARMv8? Is the intention to have a separate definition for the > >> UEFI bindings on ARMv8, so that compatibility isn't an issue? What if a > >> future version of UEFI allows LPAE usage? > > > > It is unlikely that will happen on v7 since newer versions of UEFI are > > expected to remain backwards compatible with the current spec. > > The expectation of backwards-compatibility sounds nice, but it seems a > little dangerous to outright rely on it. > > Even if not a regular compatible property, can we define a property that > indicates the UEFI revision or revision of this DT binding, so that if > we ever have to change it, there is some way of explicitly indicating > which exact schema the DT corresponds to, rather than having to > reverse-engineer it from the set of properties that "just happen" to be > present in DT? > > This is rather like the firmware node discussion that happened recently, > where we were expecting to represent a firmware (secure mode) interface > by a DT node, which would have a compatible value, which in turn would > convey information about which "OS" the secure firmware was running, and > well as any potential SoC-/OEM-/board-specific interface provided by it. > > And who knows, what if UEFI gets replaced someday; presumably we'd want > some way of explicitly stating "running under UEFI" vs. "running under > something else"? To me, these concerns are all covered by the existence of the efi-system-table node, and the version number that you can extract from the table (mandatory in any UEFI implementation) located at that address. There is no reverse-engineering involved. / Leif -- 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/