Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754044AbdCOP2z (ORCPT ); Wed, 15 Mar 2017 11:28:55 -0400 Received: from eddie.linux-mips.org ([148.251.95.138]:45718 "EHLO cvs.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753273AbdCOP1x (ORCPT ); Wed, 15 Mar 2017 11:27:53 -0400 Date: Wed, 15 Mar 2017 14:34:46 +0100 From: Ralf Baechle To: David Daney Cc: linux-mips@linux-mips.org, James Hogan , linux-kernel@vger.kernel.org, Alex Belits Subject: Re: [PATCH] MIPS: Add 48-bit VA space (and 4-level page tables) for 4K pages. Message-ID: <20170315133446.GD5512@linux-mips.org> References: <20170217012734.19256-1-david.daney@cavium.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170217012734.19256-1-david.daney@cavium.com> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1100 Lines: 27 On Thu, Feb 16, 2017 at 05:27:34PM -0800, David Daney wrote: > From: Alex Belits > > Some users must have 4K pages while needing a 48-bit VA space size. > The cleanest way do do this is to go to a 4-level page table for this > case. Each page table level using order-0 pages adds 9 bits to the > VA size (at 4K pages, so for four levels we get 9 * 4 + 12 == 48-bits. > > For the 4K page size case only we add support functions for the PUD > level of the page table tree, also the TLB exception handlers get an > extra level of tree walk. > > Signed-off-by: Alex Belits > [david.daney@cavium.com] Forward port to v4.10 > Signed-off-by: David Daney Thanks folks, queued for 4.12. While the need for 48-bit address space is not so surprising, the need for the combination of 4K pages and 48-bit address space is! I had some minor merge conflicts so it would be good if you could take a look if https://git.linux-mips.org/cgit/ralf/upstream-sfr.git/commit/?id=afba1896993a0b74aa2ad3076d594e455b3af301 looks good. Ralf