Re: [Qemu-devel] [PATCH] Add backing file option to qemu-img create help.

[Mike Day <ncmike@ncultra.org>]

On Mon, May 12, 2014 at 11:53 AM, Eric Blake <eblake@redhat.com> wrote:
> Ah, but it is:
>
> $ qemu-img create -f qcow2 -o help
> Supported options:
> size             Virtual disk size
> compat           Compatibility level (0.10 or 1.1)
> backing_file     File name of a base image
> backing_fmt      Image format of the base image
> encryption       Encrypt the image
> cluster_size     qcow2 cluster size
> preallocation    Preallocation mode (allowed values: off, metadata)
> lazy_refcounts   Postpone refcount updates
>
> and more importantly, it only appears in the help output of -f modes
> that actually support a backing file.  Contrast:
>
> $ qemu-img create -f raw -o help
> Supported options:
> size             Virtual disk size

This is much more prominent in the top-level help:

rebase [-q] [-f fmt] [-t cache] [-p] [-u] -b backing_file [-F
backing_fmt] filename