From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752781AbcHQLL4 (ORCPT ); Wed, 17 Aug 2016 07:11:56 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:54577 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752106AbcHQLLx (ORCPT ); Wed, 17 Aug 2016 07:11:53 -0400 User-Agent: K-9 Mail for Android In-Reply-To: <20160817103006.GB20762@e104818-lin.cambridge.arm.com> References: <20160816183231.21179-1-cov@codeaurora.org> <20160817103006.GB20762@e104818-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Subject: Re: [PATCH] arm64: Expose TASK_SIZE to userspace via auxv From: Christopher Covington Date: Wed, 17 Aug 2016 07:12:06 -0400 To: Catalin Marinas CC: Will Deacon , Ard Biesheuvel , Mark Rutland , Suzuki K Poulose , James Hogan , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jon Masters , Jeremy Linton Message-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On August 17, 2016 6:30:06 AM EDT, Catalin Marinas wrote: >On Tue, Aug 16, 2016 at 02:32:29PM -0400, Christopher Covington wrote: >> Some userspace applications need to know the maximum virtual address >they can >> use (TASK_SIZE). > >Just curious, what are the cases needing TASK_SIZE in user space? Checkpoint/Restore In Userspace and the Mozilla Javascript Engine https://bugzilla.mozilla.org/show_bug.cgi?id=1143022 are the specific cases I've run into. I've heard LuaJIT might have a similar situation. In general I think making allocations from the top down is a shortcut for finding a large unused region of memory. Thanks, Cov -- Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. Sent from my Snapdragon powered Android device with K-9 Mail. Please excuse my brevity.