Re: [NEW FEATURE]Partitions on loop device for 2.6

From: Bill Davidsen
Date: Tue Mar 30 2004 - 16:42:49 EST

On Mon, 29 Mar 2004, BlaisorBlade wrote:

> Alle 22:04, venerdì 2 gennaio 2004, Bill Davidsen ha scritto:
> > BlaisorBlade wrote:
> > > NEED:
> > > I have the need to loop mount files containing not plain filesystems, but
> > > whole disk images.
> > >
> > > This is especially needed when using User-mode-linux, since to run any
> > > distro installer you must partition the virtual disks(and on the host,
> > > the backing file of the disk contains a partition table).
> > >
> > > Currently this could be done by specifying a positive offset, but letting
> > > the kernel partition code handle this is better, isn't it? Would you ever
> > > accept this feature into stock kernel?
> >
> > UML is on my list of things to learn (as opposed to "try casually and
> > ignore")
> It is something a bit like VMWare. But instead of emulating hardware and
> running an OS inside that, you run a patched Linux kernel that runs as an
> userspace process on the host and provides a virtual machine, which must
> access a virtual disk, which is stored on a file.
> See for more info.
> > but have you considered using NBD?
> I didn't really know what it was, nor it seems useful for this "as is" (I've
> not really checked). Maybe that sentence means that the server program could
> do the partition parsing?
> --
> cat <<EOSIGN
> Paolo Giarrusso, aka Blaisorblade
> Linux Kernel 2.4.23/2.6.0 on an i686; Linux registered user n. 292729

No, I had in mind that using NBD you might be able to do partitions on the
network device, depending on just how much it looks like a real block
device. And since it looks as if just about anything can be a backing
store for NBD I thought it might be useful to export the file or partition
being used as the pseudo-drive and letting the UML kernel then do
partitions on it as it will. While a loopback mount looks like a partition
more than a disk, I believe the NBD actually looks like a drive.

I played with NBD long ago when it was new stuff, but what I did would
have worked as well on a partition or a device, so I have nothing to offer
but the suggestion.

bill davidsen <davidsen@xxxxxxx>
CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

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