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Re: [Libguestfs] guestmount issues with --live, but guestfish works just fine



-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org
--- Begin Message ---
On Sat, Oct 08, 2011 at 03:22:20AM -0500, Adam Miller wrote:
> On Sat, Oct 08, 2011 at 09:15:50AM +0100, Richard W.M. Jones wrote:
> <SNIP>
> > 
> > Yeah, I can sort of see what's going on here.  I think it reflects the
> > fact that --live support is not very well integrated with guestmount
> > at the moment.  Because this is a live connection, filesystems are
> > already mounted (inside the running guest) so you don't need the -m
> > option at all.  Unfortunately a bug in guestmount prevents you from
> > not using the -m option:
> > 
> >   $ guestmount --live -d FedoraRawhidex64 /tmp/mnt
> >   guestmount: must have at least one -a/-d and at least one -m/-i option
> > 
> > So at the moment without fixing that bug, it's not possible.
> > 
> > I'd be careful with using live support right now.  There are a few
> > corner cases where it doesn't behave very well.  In particular there
> > are two API calls that try to edit /etc files (OK in the appliance,
> > not so great for live guests):
> > 
> <SNIP>
> > 
> > You need to be cautious with live support and know what you're doing.
> > 
> 
> I'm really just trying to read some info from /proc ...

It can be done from guestfish, or by fixing the bug in guestmount.

> if it allowed
> --ro I'd be all over that option :)

Read-only isn't ever going to work with live access, at least not
without a lot of work.  At the protocol / API level there is no
concept of read calls vs write calls, and no need for it because for
disk images we can just use a temporary snapshot.  For live access to
have a read-only mode we'd have to classify each API, and there are
some APIs which aren't classifiable (eg. mount-ro is only "read-only"
in some narrow circumstances).

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org

--- End Message ---

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