From owner-freebsd-questions@FreeBSD.ORG Fri Nov 30 15:01:38 2012 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 59549653 for ; Fri, 30 Nov 2012 15:01:38 +0000 (UTC) (envelope-from ml@netfence.it) Received: from smtp.eutelia.it (mp1-smtp-6.eutelia.it [62.94.10.166]) by mx1.freebsd.org (Postfix) with ESMTP id EF3BD8FC19 for ; Fri, 30 Nov 2012 15:01:36 +0000 (UTC) Received: from ns2.biolchim.it (ip-188-188.sn2.eutelia.it [83.211.188.188]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.eutelia.it (Eutelia) with ESMTP id 7F00E636C66 for ; Fri, 30 Nov 2012 16:01:27 +0100 (CET) Received: from soth.ventu (adsl-ull-184-155.41-151.net24.it [151.41.155.184]) (authenticated bits=0) by ns2.biolchim.it (8.14.5/8.14.5) with ESMTP id qAUF18KY075254 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL) for ; Fri, 30 Nov 2012 16:01:15 +0100 (CET) (envelope-from ml@netfence.it) Received: from alamar.ventu (alamar.ventu [10.1.2.18]) by soth.ventu (8.14.5/8.14.5) with ESMTP id qAUF0iGC036349; Fri, 30 Nov 2012 16:00:45 +0100 (CET) (envelope-from ml@netfence.it) Message-ID: <50B8CA1C.3080207@netfence.it> Date: Fri, 30 Nov 2012 16:00:44 +0100 From: Andrea Venturoli User-Agent: Mozilla/5.0 (X11; FreeBSD i386; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: freebsd-questions@freebsd.org, mueller23@insightbb.com Subject: Re: i386 vs amd64 References: <30.96.29719.275C8B05@smtp01.insight.synacor.com> In-Reply-To: <30.96.29719.275C8B05@smtp01.insight.synacor.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.73 X-Scanned-By: MIMEDefang 2.73 on 10.1.2.13 X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (ns2.biolchim.it [192.168.2.203]); Fri, 30 Nov 2012 16:01:16 +0100 (CET) X-Spam-Score: 5.627 (*****) BAYES_20, RCVD_IN_PBL, RCVD_IN_RP_RNBL, RCVD_IN_SORBS_DUL, RDNS_DYNAMIC X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Nov 2012 15:01:38 -0000 On 11/30/12 15:40, Thomas Mueller wrote: >> On Thu, Nov 29, 2012 at 2:57 PM, Bill Tillman wrote: > >>> i386 will not see anything above 4 GB > > >> Actually you *can* give access to >4Gb RAM for your system: PAE allows you >> to use 36 bits instead of 32 to address your memory (and supported till >> Pentium Pro) but that is only for OS (32bit apps would see 4Gb only). > >> Anyway, I have not seen any troubles with 64bit installations. > >> Ilya. > > How does the system know what is OS and what is 32-bit apps? I think this question is badly written. A kernel supporting PAE can see and use more than 4GB. However, since apps runs unmodified, a single process cannot break that barrier. So, if you are running a single program that requires that lot of memory, PAE is not an option and you will need amd64. OTOH, if you run several programs which don't singularly require more than 3GB of RAM, PAE might be a viable alternative to reinstalling. > Where would GCC fit in this regard, or Clang for that matter? I don't really know, but I don't think it could make any difference. bye av.