From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NDZa8-0005iy-NL for qemu-devel@nongnu.org; Thu, 26 Nov 2009 03:20:04 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NDZa4-0005gX-SA for qemu-devel@nongnu.org; Thu, 26 Nov 2009 03:20:04 -0500 Received: from [199.232.76.173] (port=56885 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NDZa4-0005gF-JK for qemu-devel@nongnu.org; Thu, 26 Nov 2009 03:20:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:16896) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NDZa4-0004nc-7b for qemu-devel@nongnu.org; Thu, 26 Nov 2009 03:20:00 -0500 Date: Thu, 26 Nov 2009 10:19:57 +0200 From: Gleb Natapov Subject: Re: [Qemu-devel] Re: POST failure (loop) with isapc and seabios Message-ID: <20091126081957.GA5370@redhat.com> References: <20091125060951.GA17203@shareable.org> <20091125122039.GM2999@redhat.com> <20091125225349.GA18812@morn.localdomain> <20091126064925.GS2999@redhat.com> <20091126071527.GA29003@morn.localdomain> <20091126072034.GA1990@redhat.com> <20091126074846.GA32741@morn.localdomain> <20091126075642.GW2999@redhat.com> <20091126081253.GA1104@morn.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091126081253.GA1104@morn.localdomain> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin O'Connor Cc: qemu-devel@nongnu.org On Thu, Nov 26, 2009 at 03:12:53AM -0500, Kevin O'Connor wrote: > > > IMO, migrating to a new bios doesn't make sense - the bios is an > > > application with state - one can't just replace the code. > > > > > You don't migrate to a new BIOS. You migrate to a new QEMU that happens > > to have a new BIOS. And ability to migrate to a newer QEMU is a must. > > IMO, the ram at 0xf0000 needs to get migrated just like the rest of > the ram. And it is! The old BIOS is running after migration. But on the first reset after migration new BIOS should be loaded since old one can't initialize new QEMU any more. > > Silly example - Linux and APM. On Linux init, it finds the APM > vectors from bios and periodically calls them to sleep machine. On > migration, a new bios could have a different code location for apm - > if Linux calls sleep after migration it jumps into random code and > blows up. > That is not silly example. Another example is TPR patching. This examples shows why old BIOS has to be migrated and used till reboot. -- Gleb.