From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f72.google.com (mail-lf0-f72.google.com [209.85.215.72]) by kanga.kvack.org (Postfix) with ESMTP id 0A4516B0005 for ; Wed, 22 Jun 2016 16:17:58 -0400 (EDT) Received: by mail-lf0-f72.google.com with SMTP id a2so42032494lfe.0 for ; Wed, 22 Jun 2016 13:17:57 -0700 (PDT) Received: from mail-lf0-x22b.google.com (mail-lf0-x22b.google.com. [2a00:1450:4010:c07::22b]) by mx.google.com with ESMTPS id g6si1257499lbs.39.2016.06.22.13.17.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Jun 2016 13:17:56 -0700 (PDT) Received: by mail-lf0-x22b.google.com with SMTP id f6so81531490lfg.0 for ; Wed, 22 Jun 2016 13:17:56 -0700 (PDT) Date: Wed, 22 Jun 2016 23:17:54 +0300 From: Cyrill Gorcunov Subject: Re: JITs and 52-bit VA Message-ID: <20160622201754.GD2045@uranus.lan> References: <4A8E6E6D-6CF7-4964-A62E-467AE287D415@linaro.org> <576AA67E.50009@codeaurora.org> <20160622191843.GA2045@uranus.lan> <576AED88.6040805@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <576AED88.6040805@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Andy Lutomirski , Christopher Covington , Maxim Kuvyrkov , Linaro Dev Mailman List , Arnd Bergmann , Mark Brown , "linux-mm@kvack.org" , Dmitry Safonov On Wed, Jun 22, 2016 at 12:56:56PM -0700, Dave Hansen wrote: > > Yeah, cgroups don't make a lot of sense. > > On x86, the 48-bit virtual address is even hard-coded in the ABI[1]. So > we can't change *any* program's layout without either breaking the ABI > or having it opt in. > > But, we're also lucky to only have one VA layout since day one. > > 1. www.x86-64.org/documentation/abi.pdf - a??... Therefore, conforming > processes may only use addresses from 0x00000000 00000000 to 0x00007fff > ffffffff .a?? Yes, but noone forces you to write conforming programs ;) After all while hw allows you to run VA with bits > than 48 it's fine, all side effects of breaking abi is up to program author (iirc on x86 there is up to 52 bits on hw level allowed, don't have specs under my hands?) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org