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 424CEC43381 for ; Thu, 18 Mar 2021 09:56:48 +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 905B664DD8 for ; Thu, 18 Mar 2021 09:56:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 905B664DD8 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]:52802 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lMpOY-0001V6-Aq for qemu-devel@archiver.kernel.org; Thu, 18 Mar 2021 05:56:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45536) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMpNd-0000mw-1t for qemu-devel@nongnu.org; Thu, 18 Mar 2021 05:55:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:54464) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMpNa-0000w8-Vf for qemu-devel@nongnu.org; Thu, 18 Mar 2021 05:55:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616061345; 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: in-reply-to:in-reply-to:references:references; bh=iu3SEeBiTjXc7gwmJYgm4c7q8bUkvvRZGOXKSWFXeiQ=; b=SxOMjjaFzPPNmyRxXj7MTpCJ7X7ISVjPtHKboYec+2xUwNn9EsnCMVx0WbFoj5to7LLOsg jkk712lNs9nFT+f86kHQpV+lDmRzOPOa83c3YEPaWtexnpe+jeLVtCXQUyJFsATjB7eyBy XJpoEOxvTOLFASUahgQ17kAzV3ujDTQ= 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-145-PdMPKbsnOkKBG1CBaE16BQ-1; Thu, 18 Mar 2021 05:55:44 -0400 X-MC-Unique: PdMPKbsnOkKBG1CBaE16BQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 32E13A40C0; Thu, 18 Mar 2021 09:55:43 +0000 (UTC) Received: from work-vm (ovpn-115-13.ams2.redhat.com [10.36.115.13]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5AAEF5C3E6; Thu, 18 Mar 2021 09:55:42 +0000 (UTC) Date: Thu, 18 Mar 2021 09:55:39 +0000 From: "Dr. David Alan Gilbert" To: Michael Rolnik Subject: Re: of AVR target page size Message-ID: References: MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.0.5 (2021-01-21) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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=216.205.24.124; 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_H3=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: Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Michael Rolnik (mrolnik@gmail.com) wrote: > Hi Dave. > > What is the smallest supported page size? Currently 512 I think; in migration/ram.c we have: #define RAM_SAVE_FLAG_FULL 0x01 /* Obsolete, not used anymore */ #define RAM_SAVE_FLAG_ZERO 0x02 #define RAM_SAVE_FLAG_MEM_SIZE 0x04 #define RAM_SAVE_FLAG_PAGE 0x08 #define RAM_SAVE_FLAG_EOS 0x10 #define RAM_SAVE_FLAG_CONTINUE 0x20 #define RAM_SAVE_FLAG_XBZRLE 0x40 /* 0x80 is reserved in migration.h start with 0x100 next */ #define RAM_SAVE_FLAG_COMPRESS_PAGE 0x100 so we're already using the 0x100 (256) flag. I spotted this yesterday because a patch tried to use the 0x200 flag. Dave > > On Wed, Mar 17, 2021 at 10:14 PM Dr. David Alan Gilbert > wrote: > > > 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 > > > > > > -- > Best Regards, > Michael Rolnik -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK