From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:56784)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kraxel@redhat.com>) id 1ZhwDN-0001AV-Ig
	for qemu-devel@nongnu.org; Fri, 02 Oct 2015 05:01:18 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kraxel@redhat.com>) id 1ZhwDI-0006x3-JZ
	for qemu-devel@nongnu.org; Fri, 02 Oct 2015 05:01:17 -0400
Received: from mx1.redhat.com ([209.132.183.28]:41611)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kraxel@redhat.com>) id 1ZhwDI-0006wz-E3
	for qemu-devel@nongnu.org; Fri, 02 Oct 2015 05:01:12 -0400
Message-ID: <1443776468.14636.20.camel@redhat.com>
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Fri, 02 Oct 2015 11:01:08 +0200
In-Reply-To: <20151002102408.23266dc0@markmb_rh>
References: <1443701677-13629-1-git-send-email-markmb@redhat.com>
	<1443701819-13855-1-git-send-email-markmb@redhat.com>
	<1443701819-13855-7-git-send-email-markmb@redhat.com>
	<560D5057.6010308@redhat.com> <20151001160242.GA7766@morn.lan>
	<1443773786.14636.12.camel@redhat.com>
	<20151002102408.23266dc0@markmb_rh>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH v4 6/7] Make the kernel image in the fw_cfg
 DMA interface bootable
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: Marc =?ISO-8859-1?Q?Mar=ED?= <markmb@redhat.com>
Cc: Drew <drjones@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>, "Gabriel L. Somlo" <somlo@cmu.edu>, qemu-devel@nongnu.org, Kevin O'Connor <kevin@koconnor.net>, Laszlo Ersek <lersek@redhat.com>

  Hi,

> A solution that I can see is adding DMA boot capabilities to the
> linuxboot.S optionrom. I was trying to avoid this, but it looks like
> not doing so creates lots of problems. It may be better than adding a
> "nice" shortcut somewhere in QEMU or SeaBIOS.
> 
> Who uses this optionrom (and will benefit from this change)?

Any -kernel boot on x86 will use either linuxboot.bin or multiboot.bin.

>>From a compatibility point of view implementing it in the option rom
certainly has its advantages.  And as the option roms are shipped with
and loaded by qemu you don't even have to do runtime detection if that
simplifies things.  We can just build two versions of the roms and qemu
can use the one or the other depending on whenever the machine type in
question has fw_cfg dma enabled or not.

cheers,
  Gerd