Re: [Xen-devel] accessing loopback filesystem+partitions on a file

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

>       i'm sort-of helping test a xen install project where a
>       block device is presented as the DRIVE - not, i repeat
>       not, the partitions on the drive which is the quotes
>       normal quotes way of doing xen installes
>
>       (yes there are good reasons for doing this).

That's fine.  It's something that (is supposed to) works.

>       * how the hell do you loopback mount (or lvm mount
>         or _anything_! something!)  partitions that have
>         been created in a loopback'd file!!!!


You could work out where the partitions are, then use hexedit... woops!  just 
kidding ;-)

This has come up before but it's easier to find the list entries when you 
remember what you're looking for ;-)

There's a patch by NASA (of all people!) that enables the Linux loopback 
driver to support partitions:
ftp://ftp.hq.nasa.gov/pub/ig/ccd/enhanced_loopback/readme.txt

There's also the "lomount" utility from QEmu:
http://www.dad-answers.com/qemu/utilities/QEMU-HD-Mounter/lomount/
Which works out where partitions are and mounts them (no kernel mods needed).

Apparently kpartx (from the multipath tools - 
http://christophe.varoqui.free.fr/wiki/wakka.php?wiki=Home) can use the 
device mapper to create block devices for each partition.

I think I'd go with lomount, as it looks easiest.

Cheers,
Mark

>         [aside from booting up a second pre-installed xen
>         guest domain and making the filesystem-in-a-file
>         available as /dev/hdb of course.]
>
> answers of the form "work out where the partitions are, then use
> hexedit to remove the first few blocks" will win no prizes here.
>
> l.
>
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