From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=40664 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Q7ulc-0000ED-Ty for qemu-devel@nongnu.org; Thu, 07 Apr 2011 15:21:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Q7ulb-0001Ot-Ul for qemu-devel@nongnu.org; Thu, 07 Apr 2011 15:21:20 -0400 Received: from mail-gw0-f45.google.com ([74.125.83.45]:58836) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Q7ulb-0001Oo-Pc for qemu-devel@nongnu.org; Thu, 07 Apr 2011 15:21:19 -0400 Received: by gwb19 with SMTP id 19so1199467gwb.4 for ; Thu, 07 Apr 2011 12:21:19 -0700 (PDT) Message-ID: <4D9E0EAC.3020502@codemonkey.ws> Date: Thu, 07 Apr 2011 14:21:16 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] How does the QEMU load the binary files bios.bin and vgabios-cirrus.bin? References: <4D9DBC05.8010400@codemonkey.ws> <20110407153106.GA7100@redhat.com> <4D9DDB80.8090905@codemonkey.ws> <20110407155142.GB7100@redhat.com> <4D9DE166.9080001@codemonkey.ws> <4D9E045A.90500@codemonkey.ws> <20110407184417.GD7100@redhat.com> In-Reply-To: <20110407184417.GD7100@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: Jordan Justen , Bei Guan , kvm-devel , QEMU Developers On 04/07/2011 01:44 PM, Gleb Natapov wrote: >> KVM doesn't support SMM although that's not because of this. KVM >> doesn't allow execution of ROM memory which makes it difficult to >> implement PAM in the way it's intended to be implemented. This >> makes SMM a bit tricky to make work. Since there's never really >> been a pressing need to support SMM, to my knowledge, noone has even >> tried. >> > KVM allows to execute ROM memory (BIOS and option roms run this way). It > just makes it indistinguishable from RAM, but read only memory slot > support shouldn't be too hard. Why ability to execute ROM memory is > needed to support SMM though? QEMU does the leg work already to support SMM. It doesn't work with KVM because we treat SMM as ROM memory and trap read/write access. To make it work with KVM, you'd have to hack things around to switch the VGA space to RAM in order to the let the SMM code run. It's not impossible, but that's the main reason it doesn't Just Work. Regards, Anthony Liguori > -- > Gleb. >