diff options
| author | Fam Zheng <famz@redhat.com> | 2017-08-04 22:36:58 +0800 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2017-09-26 14:46:23 +0200 |
| commit | a16efd53406bc8d89f87253ab10290f8d1b145a7 (patch) | |
| tree | 279beb0668dcc8f2ffb2a6d8baa0c68ded38a669 /qemu-img.texi | |
| parent | 05b4cd5d3c20c9d7a75f0533b57b9c1c3d06e6e7 (diff) | |
qemu-img: Clarify about relative backing file options
It's not too surprising when a user specifies the backing file relative
to the current working directory instead of the top layer image. This
causes error when they differ. Though the error message has enough
information to infer the fact about the misunderstanding, it is better
if we document this explicitly, so that users don't have to learn from
mistakes.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'qemu-img.texi')
| -rw-r--r-- | qemu-img.texi | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/qemu-img.texi b/qemu-img.texi index 72dabd6b3e..90c7eab4a8 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -244,6 +244,9 @@ only the differences from @var{backing_file}. No size needs to be specified in this case. @var{backing_file} will never be modified unless you use the @code{commit} monitor command (or qemu-img commit). +If a relative path name is given, the backing file is looked up relative to +the directory containing @var{filename}. + Note that a given backing file will be opened to check that it is valid. Use the @code{-u} option to enable unsafe backing file mode, which means that the image will be created even if the associated backing file cannot be opened. A @@ -343,6 +346,9 @@ created as a copy on write image of the specified base image; the @var{backing_file} should have the same content as the input's base image, however the path, image format, etc may differ. +If a relative path name is given, the backing file is looked up relative to +the directory containing @var{output_filename}. + If the @code{-n} option is specified, the target volume creation will be skipped. This is useful for formats such as @code{rbd} if the target volume has already been created with site specific options that cannot @@ -490,6 +496,9 @@ The backing file is changed to @var{backing_file} and (if the image format of string), then the image is rebased onto no backing file (i.e. it will exist independently of any backing file). +If a relative path name is given, the backing file is looked up relative to +the directory containing @var{filename}. + @var{cache} specifies the cache mode to be used for @var{filename}, whereas @var{src_cache} specifies the cache mode for reading backing files. |