From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31F52CA90AF for ; Wed, 13 May 2020 08:33:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F55620740 for ; Wed, 13 May 2020 08:33:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589358828; bh=nB/55BO079UYamFpCt8YrKpVHQPJ94TfWCsRp/2eHes=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Z18+BdX7DUHf1ryZiyn3/5P9HFDa5GOFa0ZVTDFZWSTVRzJnMLBt9nban9GmfIGmc 893oFLrTY1z30mmEb406hp7RFQzGy0ajtewmFvhhcD02DEAE5KNiSDtrrR+sNntSoz 2LRpfW6kglTDGlyIHJ8AFpyeE9atiAn/IF/FHgxk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732297AbgEMIdr (ORCPT ); Wed, 13 May 2020 04:33:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:50072 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729726AbgEMIdr (ORCPT ); Wed, 13 May 2020 04:33:47 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9A3F920740; Wed, 13 May 2020 08:33:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589358826; bh=nB/55BO079UYamFpCt8YrKpVHQPJ94TfWCsRp/2eHes=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Onup83Bm/AReOo/jn4w37LzyOPNt+O6Pi4mx/8WRVPBGgpV8J+qw7wECUDaIsWIei eKjzA/ZtGCLeycc60TbuUWxTHoDSkRZypTwk6qUDCnncEkqAMD1hBqracK7JZPZjU3 t0cf2VETjGQNgkYPYq3LuadD27ruwnhZb/eus8HI= Date: Wed, 13 May 2020 10:33:43 +0200 From: "gregkh@linuxfoundation.org" To: "Ravich, Leonid" Cc: "Idgar, Or" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: Re: CMA enhancement - non-default areas in x86 Message-ID: <20200513083343.GA772573@kroah.com> References: <20200513064755.GA763968@kroah.com> <20200513071413.GB766804@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A: http://en.wikipedia.org/wiki/Top_post Q: Were do I find info about this thing called top-posting? A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? A: No. Q: Should I include quotations after my reply? http://daringfireball.net/2007/07/on_top On Wed, May 13, 2020 at 08:29:16AM +0000, Ravich, Leonid wrote: > PCIe NTB > Documentation/driver-api/ntb.rst > 1) Basically PCI bridge between to root complex / PCI switches > 2) using out of OS memory is one solution but then this memory is > Limited for usage by other stack, ex: get_user_pages on this memory will fail, > Therefore attempting to use it for block layer with (o_direct) will fail. > > Acutely any generic stack which attempts to "pin" this memory will fail. So why isn't the BIOS/UEFI properly reserving this from the general operating system's pages so that the driver knows to use them instead? Is UEFI wrong here about these being valid memory ranges for general use? If so, why not fix that? If not, how in the world is the OS supposed to know these memory ranges are _not_ for general use? I feel like there is something missing here... thanks, greg k-h