Re: [Qemu-devel] Stupid question?

[Jim C. Brown]

On Sun, Sep 05, 2004 at 02:41:24PM +0200, Johannes Martin wrote:
> Hi,
> 
> On Sun, 5 Sep 2004, Dieter Schicker wrote:
> > How can I mount the "virtual harddisk file" in Linux?
> > mount -t vfat -o loop /data/win98.img /mnt/win   fails!
> >
> > Any suggestions?
> Hetz already told us how to do this in his last email...
> 
> As to 'why' the above doesn't work: I assume it's because mount expects a
> hard disk partition while /data/win98.img is a complete disk (including
> the master boot record, partition table, etc), i.e. about 64 extra sectors
> at the beginning (depending on disk geometry). Right?
> 

Right. lomount gets around this by passing the offset= option to mount
(which passes it to losetup). You don't need lomount for this, you can
calculate the offset yourself. If you want to.

> BTW, has anybody worked on making it possible to mount 'cow' images on the
> host?

Sparse images should work fine w/ lomount. qemu cow images will never work,
and to use those you'd have to convert them to a regular image first.

(I lied above. There is one way to make them work, but it is fairly contorted
and twisted and not at all trivial. It'd be a massive project in itself ...
bsaicly you'd need to write a daemon that pretended to be a user-space NFS
server, and have it read/write to the cow image on the kernel's behalf. This is
extra hard because it would have to know what a FAT/NTFS/ext2/etc file system
looks like in a cow image. Easier just to convert the cow into a regular image
and use that.)

> 
>       Johannes
> 
> 
> 
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