Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755321AbbKRITH (ORCPT ); Wed, 18 Nov 2015 03:19:07 -0500 Received: from mail-wm0-f50.google.com ([74.125.82.50]:36632 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754166AbbKRITE (ORCPT ); Wed, 18 Nov 2015 03:19:04 -0500 Date: Wed, 18 Nov 2015 09:18:59 +0100 From: Ingo Molnar To: Matt Fleming Cc: Thomas Gleixner , "H . Peter Anvin" , Toshi Kani , linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, Borislav Petkov , Sai Praneeth Prakhya , Linus Torvalds , Dave Jones , Andrew Morton , Andy Lutomirski , Denys Vlasenko , Stephen Smalley Subject: Re: [PATCH 6/6] Documentation/x86: Update EFI memory region description Message-ID: <20151118081859.GB23844@gmail.com> References: <1447342823-3612-1-git-send-email-matt@codeblueprint.co.uk> <1447342823-3612-7-git-send-email-matt@codeblueprint.co.uk> <20151113092210.GB19922@gmail.com> <20151113092906.GD2716@codeblueprint.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151113092906.GD2716@codeblueprint.co.uk> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1995 Lines: 56 * Matt Fleming wrote: > On Fri, 13 Nov, at 10:22:10AM, Ingo Molnar wrote: > > > > * Matt Fleming wrote: > > > > > +We map EFI runtime services in the efi_pgd PGD in the virtual range of > > > +64Gb (arbitrarily set, can be raised if needed). The mappings are not > > > +part of any other kernel PGD and are only available during EFI runtime > > > +calls. > > > > Is that virtual address range 0-64Gb, i.e.: > > > > 0x00000000.00000000 - 0x00000010.00000000 > > > > or is it somewhere else? > > You've snipped the patch hunk that gives the address range used, > > diff --git a/Documentation/x86/x86_64/mm.txt > b/Documentation/x86/x86_64/mm.txt > index 05712ac83e38..a9885bb1ac22 100644 > --- a/Documentation/x86/x86_64/mm.txt > +++ b/Documentation/x86/x86_64/mm.txt > @@ -16,6 +16,8 @@ ffffec0000000000 - fffffc0000000000 (=44 bits) kasan > shadow memory (16TB) > ... unused hole ... > ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks > ... unused hole ... > +ffffffef00000000 - ffffffff00000000 (=64 GB) EFI region mapping space > +... unused hole ... > ffffffff80000000 - ffffffffa0000000 (=512 MB) kernel text mapping, > from phys 0 > ffffffffa0000000 - ffffffffff5fffff (=1525 MB) module mapping space > ffffffffff600000 - ffffffffffdfffff (=8 MB) vsyscalls Ah yes - but then the text is misleading, what does 'in the virtual range of 64Gb' mean? A virtual memory range is a specific range of addresses - like in the table you extended. A better phrasing would be something like: We map EFI runtime services in the 'efi_pgd' PGD in a 64Gb large virtual memory window (this size is arbitrary, it can be raised later if needed). Agreed? Thanks, Ingo -- 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/