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=-5.1 required=3.0 tests=BAYES_00,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 56796C433E0 for ; Wed, 17 Mar 2021 20:16:19 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C441264F0C for ; Wed, 17 Mar 2021 20:16:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C441264F0C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39884 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lMcaX-0007SU-PZ for qemu-devel@archiver.kernel.org; Wed, 17 Mar 2021 16:16:17 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36044) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMcYw-0006bx-GK for qemu-devel@nongnu.org; Wed, 17 Mar 2021 16:14:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:26643) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lMcYt-0002c4-1i for qemu-devel@nongnu.org; Wed, 17 Mar 2021 16:14:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616012073; 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; bh=QeNOXWub6xsTpwhc3je7ESSfpeJbvFQrkiINf6PGlyM=; b=HTUGij5kO6upNs1UgXqM97+7S4kux6N7sakbVN/jUN5CLwd7hDj8x+EnlHvzq9ZPWDlV58 fm4UcUcb6ExpyREzJhI7fPqXnQcqUzCjbU3cC44S36+knrIOiKOH3g+ARj3YqoLD92/j7q Pd/RzgXGDhCg3DkTAZXjP/W2SVRn1Zs= 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-484-EiNxyG0aM8qeQVyWE3uzGA-1; Wed, 17 Mar 2021 16:14:32 -0400 X-MC-Unique: EiNxyG0aM8qeQVyWE3uzGA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 48484801817; Wed, 17 Mar 2021 20:14:31 +0000 (UTC) Received: from work-vm (ovpn-114-138.ams2.redhat.com [10.36.114.138]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 257E25D9C0; Wed, 17 Mar 2021 20:14:28 +0000 (UTC) Date: Wed, 17 Mar 2021 20:14:26 +0000 From: "Dr. David Alan Gilbert" To: mrolnik@gmail.com Subject: of AVR target page size Message-ID: MIME-Version: 1.0 User-Agent: Mutt/2.0.5 (2021-01-21) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.251, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: philmd@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Michael, I noticed your AVR code defines: #define TARGET_PAGE_BITS 8 and has an explanation of why. Note however that's not going to work with the current live migration/snapshotting code, since you're a couple of bits smaller than the smallest page size we had so far, and for many years the RAM migration code has stolen the bottom few bits of the address as a flag field, and has already used 0x100 up; see migration/ram.c RAM_SAVE_FLAG_* - and it's actually tricky to change it, because if you change it then it'll break migration compatibility with existing qemu's. Hmm. Dave -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK