From: Horms Subject: Re: [PATCH]: kexec: framework and i386 Date: Sat, 8 Apr 2006 13:39:32 +0900 Message-ID: <20060408043929.GI4583@verge.net.au> References: <20060407074234.GA19846@verge.net.au> <4436809B.5040601@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4436809B.5040601@suse.de> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Gerd Hoffmann Cc: Magnus Damm , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On Fri, Apr 07, 2006 at 05:09:15PM +0200, Gerd Hoffmann wrote: > Hi, > > > Here is a first cut of kexec for dom0/xen, which will actually > > kexec the physical machine from xen. The approach taken is > > to move the architecture-dependant kexec code into a new hypercall. > > First you need some more security checks. On a first quick look it > seems you can zap and takeover the whole machine from within a domU by > kexec-booting the machine. Yes, I think you are right, I had completely forgotten about that. > Second I think we'll need a new kexec flag to indicate we'll go zap the > physical machine, not the virtual machine. I'm looking into the later, > and I think we'll be able to do both at some point in the future. Maybe > it is enougth to care about dom0 (physical machine kexec) vs. domU > (virtual machine kexec) only though. We certainly don't want allow > domUs kexec the whole machine, and virtual machine kexec for dom0 > doesn't make that much sense given how tight xen and dom0 work hand-in-hand. Sounds fine by me. The focus of what I was trying to achive is to zap the entire physical machine, which is what the current code does. I am actually most interested in kdump, though its not working yet. In any case a flag makes perfect sense. Though it might make sense to add it when more flexible incarnations of kexec are added. > > * kexecing into xen does not seem to work, I think that > > kexec-tools needs updating, but I have not investigated yet > > Yep, actually _alot_ of the kexec magic happens in userspace. Yes, I became aware of that along the way. I'm pretty confident that the way I have done things, if you fixed up user-space kexec so that linux -> xen worked, then xen -> xen would also work. -- Horms