From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1GXK1Y-0001zJ-TF for qemu-devel@nongnu.org; Tue, 10 Oct 2006 12:00:09 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1GXK1Y-0001ys-7h for qemu-devel@nongnu.org; Tue, 10 Oct 2006 12:00:08 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1GXK1X-0001yn-TO for qemu-devel@nongnu.org; Tue, 10 Oct 2006 12:00:07 -0400 Received: from [66.92.53.140] (helo=grelber.thyrsus.com) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA:32) (Exim 4.52) id 1GXK9L-0001Cy-NE for qemu-devel@nongnu.org; Tue, 10 Oct 2006 12:08:11 -0400 From: Rob Landley Subject: Re: [Qemu-devel] booting a linux kernel from NFS Date: Tue, 10 Oct 2006 12:00:36 -0400 References: <452BC045.20905@bluegap.ch> In-Reply-To: <452BC045.20905@bluegap.ch> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200610101200.36417.rob@landley.net> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On Tuesday 10 October 2006 11:46 am, Markus Schiltknecht wrote: > Hi, > > I get this error, when I don't give qemu a 'hda': Use "/dev/zero". (Several people have suggested that qemu should default to /dev/zero when you give it a kernel but don't give it a hard drive, but last I checked it still wasn't doing that.) > A disk image must be given for 'hda' when booting a Linux kernel. > > Why is that? Isn't it completely legal to start without a IDE drive? Because the way -kernel works is to create a fake bootsector internally, present it to the bios as the start of hda, and tell the bios to boot from that. If you haven't got an hda, it gets confused. (It probably shouldn't, since it's not actually _using_ it, but it does.) Note that if you mmap /dev/zero it counts as an anonymous mapping, so feeding in /dev/zero for hda works just fine here. Rob -- "Perfection is reached, not when there is no longer anything to add, but when there is no longer anything to take away." - Antoine de Saint-Exupery