From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 90A061381F3 for ; Wed, 9 Oct 2013 18:57:03 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 98CDBE0A6E; Wed, 9 Oct 2013 18:56:57 +0000 (UTC) Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 8C9E8E09BF for ; Wed, 9 Oct 2013 18:56:56 +0000 (UTC) Received: by mail-pa0-f44.google.com with SMTP id lf10so1505163pab.17 for ; Wed, 09 Oct 2013 11:56:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=+vnjvpp48Nd5lD/0IR6/L36D1GBl1XuSCUWklpM+ZkE=; b=Oo9sYAHJyayJeYO7FXrlQXlQ0jSIKvLbZFbkl47NAimaox6lXO5E7dlFTNPFFAZVGp bR2NKg+GfPJbO+SU5z0i5Qxa2/p6jhesCHBBX7nZnA0ZFSMbzugTj4zGG1LMoLvab2OC 5bVBzG950RIAKfDY5OgJQ1cyxZRgFwGxIRfEmUyqTztlVLGZzQchOjy752uKaqKCUSgM dCcNHV85uXVXkk1lkvmqxEOntm7FWlKyY76lQoqhEOtYtF4wsWHdUZgRl2c6nQ/pvFAk wztx9lM30eWWaqPABB2ntfgd+F9I7cdk+tOeuByeq3UX2Xp/Rg1wGOhCrgn16kliNqlV q23w== X-Received: by 10.66.182.36 with SMTP id eb4mr11005094pac.125.1381345015244; Wed, 09 Oct 2013 11:56:55 -0700 (PDT) Received: from [192.168.1.5] (213-154-212-42.static.vega-ua.net. [213.154.212.42]) by mx.google.com with ESMTPSA id tz3sm48190986pbc.20.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 09 Oct 2013 11:56:54 -0700 (PDT) Message-ID: <5255A6FB.3010404@gmail.com> Date: Wed, 09 Oct 2013 21:56:59 +0300 From: Alexander Kapshuk User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130923 Thunderbird/17.0.9 Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 To: gottlieb@nyu.edu, Alan McKinnon CC: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] re: NX (Execute Disable) protection cannot be enabled: non-PAE kernel! [dmesg] References: <52530B6D.5080707@gmail.com> <52530E8C.1040701@gmail.com> <52543B10.10201@gmail.com> <52547725.3030209@gmail.com> <87eh7vgpce.fsf@nyu.edu> In-Reply-To: <87eh7vgpce.fsf@nyu.edu> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Archives-Salt: beb2846b-740b-4d3b-a12e-deb1948ca7ec X-Archives-Hash: 72f86803b3533be1853e872777612bdd On 10/09/2013 05:17 AM, gottlieb@nyu.edu wrote: > On Tue, Oct 08 2013, Alan McKinnon wrote: > >> That is correct, with 3G physica RAM, you will not benefit from using >> PAE at all. I don't think it interferes with anything if you do have it, >> I recall a time when RedHat shipped 32 bit kernels that were PAE-enabled. >> >> Briefly, the way it works is that the kernel assigns blocks of memory to >> different processes. So a single process can still only access 4G of >> memory, but two different process don't anymore have to address the same >> 4G of memory like you must do without PAE. But you still don't get to >> give your 32 bit database more than 4g of RAM > Agreed. Virtual addresses refer to those in the program (really > process). Physical addresses address refer to those in the hardware > (i.e. addresses in the RAM itself). To have a single process able to > access extra memory would be to increase the *virtual* address range. > PAE (*physical* address extension) enables more RAM to be accessed (by > the hardware not by a single process), but does not increase the virtual > address range. > > When pdp-11s added I and D space, that increased the virtual address > range by a factor of two. The I/D bit (instruction/data) was > essentially an extra bit of virtual address. > > allan > Thanks a lot for the explanation. Much appreciated.