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 5B5BC1381F3 for ; Tue, 8 Oct 2013 21:20:53 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id A7EBAE0AC0; Tue, 8 Oct 2013 21:20:44 +0000 (UTC) Received: from mail-we0-f177.google.com (mail-we0-f177.google.com [74.125.82.177]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 7B14AE0932 for ; Tue, 8 Oct 2013 21:20:43 +0000 (UTC) Received: by mail-we0-f177.google.com with SMTP id x55so4326747wes.8 for ; Tue, 08 Oct 2013 14:20:42 -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:subject:references :in-reply-to:content-type:content-transfer-encoding; bh=q1rJrNXHU6/FmB5zG8gxdIhRT8Yq4KbiyGjpxF2xhkc=; b=p9aGmP8ExEeGrBllbBHqovoenJfRjg9ZL9w3sBqAWjAxNyR0v1ub2SijhVg3fLlude r50EgzhtQIWog/hYxgawkpo/uoANfjfxfrk1vb+9DNzKwAVSIeJJQwAOpsMmRNINqSIw 5h1xCUUt2uK1odd9weJq1nnNlohuzyyuoBntiTNh2vM2hwRmDLKz1b3rnN9QtItKDd70 RTLmEMusIXnWTnu32yTzynB17/qSmYLYxXArnQIOQ7S6Dc1u8MCkCPU4O9fPqD8w9Eb+ bacSR4LvQBzozDYQrs/DYLY4NlA+aB9Zuw3VPnC3vbqnJCh7nmD9tSmV3hdLTKEnvRD2 JT/Q== X-Received: by 10.180.109.132 with SMTP id hs4mr25632492wib.46.1381267242160; Tue, 08 Oct 2013 14:20:42 -0700 (PDT) Received: from [172.20.0.41] (196-210-126-91.dynamic.isadsl.co.za. [196.210.126.91]) by mx.google.com with ESMTPSA id c4sm8950989wiz.0.1969.12.31.16.00.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 08 Oct 2013 14:20:41 -0700 (PDT) Message-ID: <52547725.3030209@gmail.com> Date: Tue, 08 Oct 2013 23:20:37 +0200 From: Alan McKinnon User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 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: 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> In-Reply-To: <52543B10.10201@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Archives-Salt: b35409c3-b086-4bd8-a6c1-b92e62203acc X-Archives-Hash: 693307f675ce587519e07b75e45017ac On 08/10/2013 19:04, Alexander Kapshuk wrote: > On 10/07/2013 10:42 PM, Alan McKinnon wrote: >> On 07/10/2013 21:28, Alexander Kapshuk wrote: >>> Is the message below I should do something about? >>> >>> box0=; dmesg|grep -i PAE >>> [ 0.000000] Notice: NX (Execute Disable) protection cannot be >>> enabled: non-PAE kernel! >>> >>> >>> My CPU seems to have support for it. >>> box0=; grep pae /proc/cpuinfo >>> flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca >>> cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm >>> constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl >>> est tm2 ssse3 cx16 xtpr pdcm lahf_lm dtherm >>> flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca >>> cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm >>> constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl >>> est tm2 ssse3 cx16 xtpr pdcm lahf_lm dtherm >>> >>> But not my kernel, as far as I can tell. >>> box0=; uname -a >>> Linux box0 3.10.7-gentoo-r1 #1 SMP Sat Oct 5 23:57:58 EEST 2013 i686 >>> Intel(R) Pentium(R) Dual CPU T3400 @ 2.16GHz GenuineIntel GNU/Linux >>> >>> box0=; grep -i pae .config >>> box0=; echo $? >>> 1 >>> >>> Thanks. >>> >>> >> >> Symbol: ARM_LPAE [=ARM_LPAE] >> Type : unknown >> >> Symbol: X86_PAE [=n] >> Type : boolean >> Prompt: PAE (Physical Address Extension) Support >> Location: >> (1) -> Processor type and features >> Defined at arch/x86/Kconfig:1213 >> Depends on: X86_32 [=n] && !HIGHMEM4G [=n] >> Selected by: HIGHMEM64G [=n] && && !M486 [=n] >> >> > Thanks. I did a little research into the whole PAE business, as > obviously my knowledge of the matter in question was limited. > > If I understood it correctly, PAE is a method that allows 32-bit kernels > access 4 or more Gb of RAM, which is normally the domain of 64-bit kernels. > > Seeing I've got 3 Gb of RAM, I arrived at the conclusion I don't need > PAE enabled, do I? > > box0=; sed 1q /proc/meminfo > MemTotal: 3107668 kB 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 -- Alan McKinnon alan.mckinnon@gmail.com