From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:43826)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1UX4vd-0006wn-85
	for qemu-devel@nongnu.org; Tue, 30 Apr 2013 03:24:46 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1UX4vY-0006lb-6p
	for qemu-devel@nongnu.org; Tue, 30 Apr 2013 03:24:45 -0400
Received: from mail-ee0-f48.google.com ([74.125.83.48]:41011)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <paolo.bonzini@gmail.com>) id 1UX4vY-0006lJ-0c
	for qemu-devel@nongnu.org; Tue, 30 Apr 2013 03:24:40 -0400
Received: by mail-ee0-f48.google.com with SMTP id d49so82878eek.7
	for <qemu-devel@nongnu.org>; Tue, 30 Apr 2013 00:24:39 -0700 (PDT)
Sender: Paolo Bonzini <paolo.bonzini@gmail.com>
Message-ID: <517F71A7.10303@redhat.com>
Date: Tue, 30 Apr 2013 09:24:23 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
MIME-Version: 1.0
References: <1367137941-4310-1-git-send-email-jordan.l.justen@intel.com>
	<1367137941-4310-7-git-send-email-jordan.l.justen@intel.com>
	<517E2D63.6030700@redhat.com>
	<CAFe8ug_Q8Z95DVr+BUTDw9nYt1kXv_g_1zedKrOvbspiUxNnvA@mail.gmail.com>
	<517EE1B9.90609@redhat.com>
	<CAFe8ug-QmV0PsmjkLXa1w-wC9SghNNQ4dm098Op0OBCFPQy7Ew@mail.gmail.com>
In-Reply-To: <CAFe8ug-QmV0PsmjkLXa1w-wC9SghNNQ4dm098Op0OBCFPQy7Ew@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH 6/6] pc_sysfw: change rom_only default to 0
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Jordan Justen <jljusten@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>

Il 30/04/2013 05:51, Jordan Justen ha scritto:
> The rom in qemu is read-only. In kvm, it has been read-write. That is
> different behavior.

And it was a problem, hence it was reverted.

> I assume with kvm readonly support, at some point the rom may be
> read-only or read/write under kvm depending on the capabilities.

No, this would be bad.

> Anyway, would this work:
> if (-pflash is not used) {
>   qemu and kvm always use a 'rom' mode
> } else if (non-kvm or kvm read-only capable) {
>   PC flash used
> } else {
>   die "kvm+pflash requires read-only capability"
> }
> 
> Someone could create a flash capable VM on qemu or newer kvm, and then
> have trouble with it on an older kvm, but the chance of potential
> issues seems greatly reduced.
> 
> For people using rom firmware, this should have no impact.

Yes, _this_ would work because it requires a special command line, and
it would have never worked before.

Paolo