Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161599Ab3FUQnK (ORCPT ); Fri, 21 Jun 2013 12:43:10 -0400 Received: from terminus.zytor.com ([198.137.202.10]:58063 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161570Ab3FUQnI (ORCPT ); Fri, 21 Jun 2013 12:43:08 -0400 Message-ID: <51C4827B.7090208@zytor.com> Date: Fri, 21 Jun 2013 09:42:35 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130514 Thunderbird/17.0.6 MIME-Version: 1.0 To: Borislav Petkov CC: Matthew Garrett , James Bottomley , Ingo Molnar , Linux EFI , Matt Fleming , X86 ML , LKML , Borislav Petkov Subject: Re: [PATCH -v2 0/4] EFI 1:1 mapping References: <20130620170124.GA19877@pd.tnic> <20130620171210.GA26593@srcf.ucam.org> <20130620180808.GB19877@pd.tnic> <20130620181015.GA27833@srcf.ucam.org> <20130620181445.GA791@pd.tnic> <20130620181731.GA27960@srcf.ucam.org> <20130620184736.GC19877@pd.tnic> <51C383AC.4060706@zytor.com> <20130621072356.GA22006@pd.tnic> <20130621142101.GG22006@pd.tnic> In-Reply-To: <20130621142101.GG22006@pd.tnic> X-Enigmail-Version: 1.5.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1331 Lines: 34 On 06/21/2013 07:21 AM, Borislav Petkov wrote: > On Fri, Jun 21, 2013 at 03:05:30AM -0700, H. Peter Anvin wrote: >> If you cap it you are basically imposing a constraint on the firmware >> and may not run properly (or at least have to turn off EFI runtime >> calls with all that implies.) > > I don't want to cap EFI just for the fun of it but rather set a limit > so that the next one who wants a chunk of the virtual address space can > have a reliable limit from where she/he can start. Otherwise we won't > know where EFI reliably ends... > We don't... and I don't think there is anything we can do about it. If some messed-up firmware wants to map a terabyte we either refuse and don't allow EFI runtime calls on that machine or we accept it. Fortunately the space is extremely large and with growing down from a known address it is less likely that we'll conflict with something. >> It might be good to have a sanity check but it needs to be pretty >> generous. > > 64 Gb generous enough? Let's start there and see if we run into something that gives us trouble. -hpa -- 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/