Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754645Ab2JBPlP (ORCPT ); Tue, 2 Oct 2012 11:41:15 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:59837 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752625Ab2JBPlN (ORCPT ); Tue, 2 Oct 2012 11:41:13 -0400 Date: Tue, 2 Oct 2012 16:39:39 +0100 From: Catalin Marinas To: Jon Masters Cc: "linux-kernel@vger.kernel.org" , Arnd Bergmann , Will Deacon Subject: Re: [PATCH 10/36] AArch64: MMU definitions Message-ID: <20121002153939.GH25708@arm.com> References: <1341608777-12982-1-git-send-email-catalin.marinas@arm.com> <1341608777-12982-11-git-send-email-catalin.marinas@arm.com> <506A3898.7000804@jonmasters.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <506A3898.7000804@jonmasters.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1428 Lines: 32 On Tue, Oct 02, 2012 at 01:43:04AM +0100, Jon Masters wrote: > On 07/06/2012 05:05 PM, Catalin Marinas wrote: > > > +/* > > + * PAGE_OFFSET - the virtual address of the start of the kernel image. > > + * VA_BITS - the maximum number of bits for virtual addresses. > > + * TASK_SIZE - the maximum size of a user space task. > > + * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area. > > + * The module space lives between the addresses given by TASK_SIZE > > + * and PAGE_OFFSET - it must be within 128MB of the kernel text. > > + */ > > +#define PAGE_OFFSET UL(0xffffffc000000000) > > +#define MODULES_END (PAGE_OFFSET) > > +#define MODULES_VADDR (MODULES_END - SZ_64M) > > +#define VA_BITS (39) > > +#define TASK_SIZE_64 (UL(1) << VA_BITS) > > Pedantic nit pick. Shouldn't that "it must be within 128MB of the kernel > text" be "within 128MB of the *end* of the kernel text"? The point being > that on AArch64 unconditional branches are encoded as imm26+1 (27 bits) > and so you're going with -64MB to ensure that you're within the range. I read it to be within 128MB of any part of the kernel text but I can change it to "end of" if that's clearer. -- Catalin -- 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/