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Date: Tue, 7 Dec 2010 20:36:47 +0000
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Subject: Re: [Qemu-devel] [PATCH 1/1] qemu-img.c: Clean up handling of image
	size in img_create()
From: Stefan Hajnoczi <stefanha@gmail.com>
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To: Jes.Sorensen@redhat.com
Cc: kwolf@redhat.com, qemu-devel@nongnu.org

On Tue, Dec 7, 2010 at 5:39 PM,  <Jes.Sorensen@redhat.com> wrote:
> =A0 =A0 // The size for the image must always be specified, with one exce=
ption:
> =A0 =A0 // If we are using a backing file, we can obtain the size from th=
ere
> - =A0 =A0if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n =3D=3D =
-1) {
> -
> + =A0 =A0if (get_option_parameter(param, BLOCK_OPT_SIZE)->value.n =3D=3D =
0) {
> =A0 =A0 =A0 =A0 QEMUOptionParameter *backing_file =3D
> =A0 =A0 =A0 =A0 =A0 =A0 get_option_parameter(param, BLOCK_OPT_BACKING_FIL=
E);
> =A0 =A0 =A0 =A0 QEMUOptionParameter *backing_fmt =3D

Today it is possible to create 0 byte sized images.  Your patch will
change that:
If there is a backing file, then the size will be taken from the backing fi=
le.
If there is no backing file, then an error about missing size will be
printed, even though a size of 0 has been given.

I don't think 0 sized images are very useful, but I'm not sure we
should make this change.

Stefan