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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 106DDC0650F for ; Wed, 14 Aug 2019 06:14:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DCAE72133F for ; Wed, 14 Aug 2019 06:14:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="XNTqUbcz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727195AbfHNGOW (ORCPT ); Wed, 14 Aug 2019 02:14:22 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:60140 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725265AbfHNGOW (ORCPT ); Wed, 14 Aug 2019 02:14:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=44K07C207hP60aYqx/O6kvlLTyW56Ovhtuazmf91s3M=; b=XNTqUbczBcUcBbsb2phecwHjD /lGxXibOWPO99uMOTbuOoALJusaNcHor07dCMalkCClPs3nQt/P8CvClvz2yHRNX4jZwXF3D+om5T vB5pbbOJMSjhtIoVYDrnj3tQf+pOhrr8SDPfu4Z96z5i50/E9jiQ2Q+2uLpwgIkwVNH/AOCANk1H7 CmOBRSMduJImu+WNej5byXvQHT/nhYc7ifGAGEMMtpK6Ob489BB07q5Q9YbJh16eQQseDdqPzRZU+ nXjkTeROgopU8iLe44RqQC1qHEvtnpXAgFR9q96FXFTjN/yfjSEtQXPjF6XPwsHg1aBHfRiFsfM3I 51ChTttGQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.92 #3 (Red Hat Linux)) id 1hxmY8-0005Tu-P2; Wed, 14 Aug 2019 06:14:21 +0000 Date: Tue, 13 Aug 2019 23:14:20 -0700 From: Christoph Hellwig To: Christophe Leroy Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, npiggin@gmail.com, Paul Mackerras , linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH v1 05/10] powerpc/mm: Do early ioremaps from top to bottom on PPC64 too. Message-ID: <20190814061420.GA17453@infradead.org> References: <6bc35eca507359075528bc0e55938bc1ce8ee485.1565726867.git.christophe.leroy@c-s.fr> <019c5d90f7027ccff00e38a3bcd633d290f6af59.1565726867.git.christophe.leroy@c-s.fr> <20190814055525.GA12744@infradead.org> <1d44ec1d-339d-e22c-2133-175e0aa745f6@c-s.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1d44ec1d-339d-e22c-2133-175e0aa745f6@c-s.fr> User-Agent: Mutt/1.11.4 (2019-03-13) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 14, 2019 at 08:10:59AM +0200, Christophe Leroy wrote: > > Note that while a few other architectures have a magic hack like powerpc > > to make ioremap work before vmalloc, the normal practice would be > > to explicitly use early_ioremap. I guess your change is fine for now, > > but it might make sense convert powerpc to the explicit early_ioremap > > scheme as well. > > > > I've been looking into early_ioremap(), but IIUC early_ioremap() is for > ephemeral mappings only, it expects all early mappings to be gone at the end > of init. Yes. > PPC installs definitive early mappings (for instance for PCI). How does that > have to be handled ? Good question, and no good answer. I've just been looking at a generic ioremap for simple architectures, and been finding all kinds of crap and inconsistencies, and this is one of the things I noticed.