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=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,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 BDAEBC433B4 for ; Fri, 9 Apr 2021 14:17:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DB3860FF1 for ; Fri, 9 Apr 2021 14:17:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233828AbhDIORM (ORCPT ); Fri, 9 Apr 2021 10:17:12 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:30097 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232286AbhDIORK (ORCPT ); Fri, 9 Apr 2021 10:17:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617977817; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7lJbgd2hYY827G0NWvg1oy4yBkmSJegYFDEkQ7hgRxA=; b=BYqB95MhceHs4AJrUa8zlRHyTswcZ3H4qKTPhdoCsFBLGuy3c9IgksPYJQyT31zGxOmQww Ufy76vJXnvRvJy1up6koXtM7ozgLlysc/SOO5DKKFKP63CDYJ5gfrcyP/aFeyz//tLTxox U70cLgQRoffXjJSGSpCZCRtGFnGW4fA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-554-CbpfF08qOAm3ydVeGePGJg-1; Fri, 09 Apr 2021 10:16:55 -0400 X-MC-Unique: CbpfF08qOAm3ydVeGePGJg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 39E0B807344; Fri, 9 Apr 2021 14:16:54 +0000 (UTC) Received: from [10.36.115.11] (ovpn-115-11.ams2.redhat.com [10.36.115.11]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6FF2A648A1; Fri, 9 Apr 2021 14:16:51 +0000 (UTC) Subject: Re: [PATCH v7] RISC-V: enable XIP To: Mike Rapoport Cc: Alex Ghiti , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, Vitaly Wool References: <20210409065115.11054-1-alex@ghiti.fr> <3500f3cb-b660-5bbc-ae8d-0c9770e4a573@ghiti.fr> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <2d442bca-c367-598c-b4ee-746925517118@redhat.com> Date: Fri, 9 Apr 2021 16:16:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09.04.21 16:10, Mike Rapoport wrote: > On Fri, Apr 09, 2021 at 02:07:24PM +0200, David Hildenbrand wrote: >> On 09.04.21 13:39, Alex Ghiti wrote: >>> Hi David, >> >> I assume you still somehow create the direct mapping for the kernel, right? >> So it's really some memory region with a direct mapping but without a memmap >> (and right now, without a resource), correct? > > XIP kernel text is not a region in memory to begin with ;-) I think that's the part that confused me. I thought it would be mapped somehow into physical address space and would be addressed like other memory -- just that reads would be rewired to go to flash. > > It resides in a flash and it is executed directly from there without being > relocated to RAM. > > That's why it does not need neither direct mapping, nor struct pages. Thanks for clarifying! :) -- Thanks, David / dhildenb