From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1033306AbdDXWC1 (ORCPT ); Mon, 24 Apr 2017 18:02:27 -0400 Received: from mail-wm0-f50.google.com ([74.125.82.50]:38145 "EHLO mail-wm0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S978637AbdDXWCJ (ORCPT ); Mon, 24 Apr 2017 18:02:09 -0400 Date: Tue, 25 Apr 2017 01:01:58 +0300 From: "Kirill A. Shutemov" To: John Paul Adrian Glaubitz Cc: "Kirill A. Shutemov" , linux-kernel@vger.kernel.org, Andi Kleen , Dave Hansen , Andy Lutomirski , Michal Hocko , linux-arch@vger.kernel.org, linux-mm@kvack.org Subject: Re: Question on the five-level page table support patches Message-ID: <20170424220158.z67cir7sjfyn4wdt@node.shutemov.name> References: <030ea57b-5f6c-13d8-02f7-b245a754a87d@physik.fu-berlin.de> <20170424161959.c5ba2nhnxyy57wxe@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170306 (1.8.0) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 24, 2017 at 10:37:40PM +0200, John Paul Adrian Glaubitz wrote: > On 04/24/2017 06:19 PM, Kirill A. Shutemov wrote: > > In proposed implementation, we also use hint address, but in different > > way: by default, if hint address is NULL, kernel would not create mappings > > above 47-bits, preserving compatibility. > > Ooooh, that would solve a lot of problems actually if it were to be available > on all architectures. On SPARC, the situation is really annoying and I have > been discussing a solution with the Qt developers and they suggested a > similar approach, just one that would also apply to brk() [1]. > > > If an application wants to have access to larger address space, it has to > > specify hint addess above 47-bits. > > > > See details here: > > > > http://lkml.kernel.org/r/20170420162147.86517-10-kirill.shutemov@linux.intel.com > > Thanks. I'll have a read. Although from your message I'm reading out that > this particular proposal got rejected. No. I just wasn't applied yet, so situation may change. > Would be really nice to able to have a canonical solution for this issue, > it's been biting us on SPARC for quite a while now due to the fact that > virtual address space has been 52 bits on SPARC for a while now. Power folks are going to implement similar approach. I don't see why Sparc can't go the same route. -- Kirill A. Shutemov