From owner-freebsd-current@FreeBSD.ORG Mon Nov 22 18:37:48 2010 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EDC27106566B for ; Mon, 22 Nov 2010 18:37:47 +0000 (UTC) (envelope-from alan.l.cox@gmail.com) Received: from mail-fx0-f54.google.com (mail-fx0-f54.google.com [209.85.161.54]) by mx1.freebsd.org (Postfix) with ESMTP id 528138FC14 for ; Mon, 22 Nov 2010 18:37:46 +0000 (UTC) Received: by fxm19 with SMTP id 19so5334193fxm.13 for ; Mon, 22 Nov 2010 10:37:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:reply-to :in-reply-to:references:date:message-id:subject:from:to:cc :content-type; bh=oS3vriV71WNUloF/2y0g7B1Nd+enOk7V/Y2RqAajOzs=; b=xvFEhrL6uCBKQoMlwhcBq+ya84wU2/ahxNoTPl/lPLUUdsNdwVHRZHl/OTiX2Zoq0+ m09rYKiEJ/skoau6iduRhpSElcpIigoIRBYorYdfV9pduO14CL1QEp+9016uwOFGqzuj D0XKNQPw+RsDsCkCnoCDkuEMc82vMUrEBXyGo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:reply-to:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; b=c+5xSPaqt8FeBhtBIf3/GDW49b9Zj1T8C8xLJGLy7YibodCtLpPl4OPSjsyC0yzEqz MGckeTA4XpWLcvYKIM+CtI+zlxiQxhjX/PZRfPE77VHlMvlr2oJmSKz5dO4WZSw07drC oHO3CJSL2Bmscj7I3E5DkcFcJDIbqhWwiNaC8= MIME-Version: 1.0 Received: by 10.223.70.208 with SMTP id e16mr2555304faj.6.1290451065949; Mon, 22 Nov 2010 10:37:45 -0800 (PST) Received: by 10.223.116.205 with HTTP; Mon, 22 Nov 2010 10:37:45 -0800 (PST) In-Reply-To: <201011220759.16082.jhb@freebsd.org> References: <1290387926.16558.1283.camel@home-yahoo> <201011220759.16082.jhb@freebsd.org> Date: Mon, 22 Nov 2010 12:37:45 -0600 Message-ID: From: Alan Cox To: John Baldwin Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-current@freebsd.org, Sean Bruno Subject: Re: 40 vs 44 bit memory addressing HP DL580/980 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: alc@freebsd.org List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 Nov 2010 18:37:48 -0000 On Mon, Nov 22, 2010 at 6:59 AM, John Baldwin wrote: > On Sunday, November 21, 2010 8:05:26 pm Sean Bruno wrote: > > Looks like these HP boxes have the capability to do 44 bit memory > > addressing if configured to do so from the BIOS. > > > > Is anyone interested in any data from that setting? > > Does it boot ok? :) The MTRR code should handle that (there is a CPUID > field that tells the OS how many bits are significant). Not sure if there > are any places in the pmap that assume 40 bits, but a test boot is > certainly > worth trying. > > Since we don't boot with 40-bit addressing, I can easily predict the outcome. :-) The trouble with this machine is that the second 128GB of RAM is being placed between 512G and 1T in the physical address space, which is beyond the range of the (current) direct map. So, we take a page fault on the first access to a page in the second 128GB through the direct map. Alan