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=2.5 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 4C573C433DB for ; Wed, 17 Mar 2021 21:34:47 +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 9D74E64F09 for ; Wed, 17 Mar 2021 21:34:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D74E64F09 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46504 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lMdoT-000524-Ju for qemu-devel@archiver.kernel.org; Wed, 17 Mar 2021 17:34:45 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52974) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMdn1-00047h-By for qemu-devel@nongnu.org; Wed, 17 Mar 2021 17:33:15 -0400 Received: from mail-qv1-xf32.google.com ([2607:f8b0:4864:20::f32]:33412) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lMdmz-000522-RV for qemu-devel@nongnu.org; Wed, 17 Mar 2021 17:33:15 -0400 Received: by mail-qv1-xf32.google.com with SMTP id o19so2214720qvu.0 for ; Wed, 17 Mar 2021 14:33:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=iE+xGoqKvaQE9pmhZmaSG4av+1bMkr7lb2FxmtQxirs=; b=MSkEWUwU6dPzRpKY1GUJLrwhrNlNv9gn4W+uUEtO4xv3D8W3z+IJI3FLbVqzJbTVKq shlL2gbvsbS0Dg2J0KYzL0a0a6wAYWoA8TPAFnUUcbaPDGzRM0F4ZG4vdUXvTDfMYEM0 GXkQOewJTfs7/ychaZzTBPTMvKEoflvPPw52OV/oSId8+sjmk+EHcMdVL4dktnlHjxN8 rmFhruuMj2VdP7wL6M8IxpK0JYhA2bSnoa3lYgaA1s2dfMJZFKMCXzDYko64w8Fsi03Z sQnW2FJcEZOPZhTn2k+DtIMVMeRBJZ9iT1UDhN4fraPkVxSxoaRBELIR9XCg/lI6lysU 0+fQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=iE+xGoqKvaQE9pmhZmaSG4av+1bMkr7lb2FxmtQxirs=; b=cjAZSUvdLZO9rkBnWWLygwM0W6nNDxqDCEqlyi4LC9pdMs5INxNeYldx/7hFwsK3Vz PYZ5ziSCxMccKiZ65zKO0D+CoqdtBCqtPjc0cEGTgza/HfBIhYKIvdRrhA0BS8JKGbNe 2ULqwxK9XnIBMglnZV3gHyuyP1oFGG7FLmDJtPfEA0U29kmpvhmnkzeJMAsa+B1eUxai TOQS0aCWTAFbmsIdpa5FY3dIT/PJFaECy7GYx2GOAgrx7Dy2S7JcxAS+6HMrDC+/1qA0 Mrv/ztQ9pmBNjS6pcKQzuxgxCgqDxPSeq7IMoB7RKhQl1Deq6hL8/JG277YzlSaF5JZg S76Q== X-Gm-Message-State: AOAM530ZZ9+lMsb0M9WN63yonKFyPY5h7YbdyswoIPU52ZgltZelTmQe Eo9Y3vj6ZZke0AelMlMDv8HfPYHXVB/GeG+HbyI= X-Google-Smtp-Source: ABdhPJwQTqdpj82yQYd1XUhJv40Iem7Z17oX2k86SsOMw7PRfno3zcgRfFXip9zotvm/iO9w843FDie7swH16aHIbHY= X-Received: by 2002:ad4:52c2:: with SMTP id p2mr1210612qvs.45.1616016792175; Wed, 17 Mar 2021 14:33:12 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Michael Rolnik Date: Wed, 17 Mar 2021 23:32:36 +0200 Message-ID: Subject: Re: of AVR target page size To: "Dr. David Alan Gilbert" Content-Type: multipart/alternative; boundary="000000000000d9486d05bdc23af2" Received-SPF: pass client-ip=2607:f8b0:4864:20::f32; envelope-from=mrolnik@gmail.com; helo=mail-qv1-xf32.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, 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: =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --000000000000d9486d05bdc23af2 Content-Type: text/plain; charset="UTF-8" Hi Dave. What is the smallest supported page size? 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 --000000000000d9486d05bdc23af2 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi Dave.

What is the smallest supported= page size?


On Wed, Mar 17, 2021 at 10:14 PM Dr. David = Alan Gilbert <dgilbert@redhat.com= > wrote:
= Hi Michael,
=C2=A0 I noticed your AVR code defines:

=C2=A0 #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_*=C2=A0 =C2=A0 - and it's actually tricky to change it, b= ecause 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
--000000000000d9486d05bdc23af2--