From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH 0/4] EFI 1:1 mapping Date: Mon, 03 Jun 2013 14:19:05 -0700 Message-ID: <1370294345.9888.12.camel@dabdike> References: <20130603081148.GB13607@nazgul.tnic> <1370269642.2910.4.camel@dabdike> <20130603143010.GA20252@srcf.ucam.org> <1370270282.2910.9.camel@dabdike> <20130603152122.GA21312@srcf.ucam.org> <1370276286.2910.29.camel@dabdike> <20130603162435.GA22563@srcf.ucam.org> <1370277307.2910.39.camel@dabdike> <20130603164237.GA23146@srcf.ucam.org> <1370282703.9888.5.camel@dabdike> <20130603181110.GA25060@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130603181110.GA25060-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Matthew Garrett Cc: Borislav Petkov , Linux EFI , Matt Fleming , Jiri Kosina , X86-ML , LKML , Borislav Petkov List-Id: linux-efi@vger.kernel.org On Mon, 2013-06-03 at 19:11 +0100, Matthew Garrett wrote: > > > The problem there is that you're saying "In theory". We know that > > > Windows doesn't behave this way, so we have no legitimate expectation > > > that it'll work. We know that it doesn't on some Apple hardware. > > > > Fine, you say we need to call SetVirtualAddressMap because windows does, > > I agree, I'm just saying we get additional safety from calling it with > > the 1:1 map ... I don't see what the problem is. > > No. I'm saying that calling it with the 1:1 map is something very > different to the behaviour of Windows, and I'm saying that doing so is > known to cause variable writes on some Apple hardware to stop working. > If we're aiming for maximum compatibility, we need to call > SetVirtualAddressMap() with addresses above the canonicalisation hole. OK, so tell me this problem: it's a new one one me. I think you're saying if we don't call SetVirtualAddressMap with a mapping above a certain value, some Apple system breaks somehow? (how?). James