From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from tx2outboundpool.messaging.microsoft.com (tx2ehsobe001.messaging.microsoft.com [65.55.88.11]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 525E22C00BE for ; Fri, 3 May 2013 03:14:08 +1000 (EST) Date: Thu, 2 May 2013 12:13:59 -0500 From: Scott Wood Subject: Re: pci overmapping To: Yoder Stuart-B08248 References: <9F6FE96B71CF29479FF1CDC8046E15035C8E18@039-SN1MPN1-002.039d.mgd.msft.net> In-Reply-To: <9F6FE96B71CF29479FF1CDC8046E15035C8E18@039-SN1MPN1-002.039d.mgd.msft.net> (from B08248@freescale.com on Thu May 2 12:05:42 2013) Message-ID: <1367514839.24411.12@snotra> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Cc: Sethi Varun-B16395 , "linuxppc-dev@lists.ozlabs.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 05/02/2013 12:05:42 PM, Yoder Stuart-B08248 wrote: > Kumar, >=20 > In fsl_pci.c there is a change you made a while back: > "powerpc/fsl: Setup PCI inbound window based on actual amount of =20 > memory" >=20 > ...and there is this comment in the code: >=20 > /* PCIe can overmap inbound & outbound since RX & TX are =20 > separated */ > if (early_find_capability(hose, 0, 0, PCI_CAP_ID_EXP)) { >=20 > You are implying that PCIe can overmap and PCI can't. Why is > that? (I'm assuming that 'overmap' means that inbound window > can extend beyond the end of ram.) Shouldn't the concern be whether we're overlapping outbound, not merely =20 whether we go beyond the end of RAM? And couldn't inbound/outbound overlap be an issue even on PCIe, if =20 there's a PCI bridge underneath it? -Scott=