From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH -v2 0/4] EFI 1:1 mapping Date: Thu, 20 Jun 2013 15:35:24 -0700 Message-ID: <51C383AC.4060706@zytor.com> References: <1371740019.2372.3.camel@dabdike> <20130620162916.GA25727@srcf.ucam.org> <1371746775.2372.11.camel@dabdike> <20130620165426.GB26214@srcf.ucam.org> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130620184736.GC19877-fF5Pk5pvG8Y@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Borislav Petkov Cc: Matthew Garrett , James Bottomley , Ingo Molnar , Linux EFI , Matt Fleming , X86 ML , LKML , Borislav Petkov List-Id: linux-efi@vger.kernel.org On 06/20/2013 11:47 AM, Borislav Petkov wrote: > > I guess we can do a top-down allocation, starting from the highest > virtual addresses: > > EFI_HIGHEST_ADDRESS > | > | size1 > | > --> region1 > | > | size2 > | > --> region2 > > ... > > and we make EFI_HIGHEST_ADDRESS be the same absolute number on every > system. > > hpa, is this close to what you had in mind? It would be prudent to > verify whether this will suit well with the kexec virtual space layout > though... > This would work really well, I think. The tricky part here is to pick a safe EFI_HIGHEST_ADDRESS as it is an ABI. My preference would be to make EFI_HIGHEST_ADDRESS = -4 GB, which is *not* what Windows uses, but will leave the high negative range clear, and allows a range where we can grow down without much risk of interfering with anything else. -hpa