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Re: [Qemu-devel] Re: Boot Failure (CDROM boot failure code : 0004)

Subject: Re: [Qemu-devel] Re: Boot Failure CDROM boot failure code : 0004
From: Jens Axboe
Date: Mon, 16 Jun 2008 20:00:28 +0200
On Mon, Jun 16 2008, Paul Brook wrote:
> On Monday 16 June 2008, Jens Axboe wrote:
> > On Mon, Jun 16 2008, Volkan YAZICI wrote:
> > > On Mon, 16 Jun 2008, Laurent Vivier <[email protected]> writes:
> > > > could you burn a CD with your .iso and try to boot a real PC ?
> > >
> > > I created the ISO image from the same CD that's inserted into the
> > > /dev/scd0 using below command:
> > >
> > >   root:~# dd bs=$[1024 * 32] \
> > >
> > >   > if=/dev/scd0 \
> > >   > of=/root/windows-server-2003-standard-x86-64-sp2.iso
> > >
> > > And I'm sure CD is bootable. (Not pirated, original.) OTOH, if we'd
> > > assume the ISO image is corrupted for some unknown reason, why "-cdrom
> > > /dev/scd0" didn't work?
> >
> > You can't just do a dd and expect the output to be bootable, that wont
> > include the floppy boot image.
> 
> Are you sure? 
> Copying all the files and creating a new iso image won't work, but I'm fairly 
> sure dd should. My understanding is that the image (which is effectively what 
> dd gives you) contains all the data for the el torito bits, but they're not 
> neccly accessible via the mounted filesystem.

I was slightly off, in hindsight, didn't think properly about that
before replying :-)

The dd image should indeed be bootable, but a burned version of the
image will not be. And copying alone will of course not work.

Sorry for the misinformation!

-- 
Jens Axboe



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