From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx180.postini.com [74.125.245.180]) by kanga.kvack.org (Postfix) with SMTP id B83A16B0005 for ; Wed, 10 Apr 2013 22:49:06 -0400 (EDT) Message-ID: <51662492.1030100@zytor.com> Date: Wed, 10 Apr 2013 19:48:50 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH] x86: add phys addr validity check for /dev/mem mmap References: <1364905733-23937-1-git-send-email-fhrbata@redhat.com> <515B2802.1050405@zytor.com> <515CD359.40004@gmail.com> <515CD3BF.5010104@zytor.com> <5166229D.2090904@gmail.com> In-Reply-To: <5166229D.2090904@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Simon Jeons Cc: Frantisek Hrbata , linux-kernel@vger.kernel.org, linux-mm@kvack.org, tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, oleg@redhat.com, kamaleshb@in.ibm.com On 04/10/2013 07:40 PM, Simon Jeons wrote: > Hi H.Peter, > On 04/04/2013 09:13 AM, H. Peter Anvin wrote: >> On 04/03/2013 06:11 PM, Simon Jeons wrote: >>> Why we consider boot_cpu_data.x86_phys_bits instead of e820 map here? >>> >> Because x86_phys_bits is what controls how much address space the >> processor has. e820 tells us how much *RAM* the machine has, or >> specifically, how much RAM the machine had on boot. > > I have 8GB memory in my machine, but when I accumulated every e820 > ranges which dump in dmesg, there are 25MB memory less then 8GB(1024*8) > memory, why 25MB miss? > For whatever reason your BIOS is stealing some memory, possibly for video. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- 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