[Qemu-devel] qemu-img help missing backing file

[Qemu-devel] qemu-img help missing backing file

[Alexander Graf]

Howdy,

I just wanted to create a backed qcow2 image and was irritated by qemu-img not showing me the correct command line option. It's just missing from the list:

> agraf@s390t27:~/git/qemu> ./qemu-img --help
> qemu-img version 0.12.50, Copyright (c) 2004-2008 Fabrice Bellard
> usage: qemu-img command [command options]
> QEMU disk image utility
> 
> Command syntax:
>   check [-f fmt] filename
>   create [-f fmt] [-o options] filename [size]

^- missing -b

>   commit [-f fmt] filename
>   convert [-c] [-f fmt] [-O output_fmt] [-o options] filename [filename2 [...]] output_filename
>   info [-f fmt] filename
>   snapshot [-l | -a snapshot | -c snapshot | -d snapshot] filename
>   rebase [-f fmt] [-u] -b backing_file [-F backing_fmt] filename
> 
> Command parameters:
>   'filename' is a disk image filename
>   'fmt' is the disk image format. It is guessed automatically in most cases
>   'size' is the disk image size in bytes. Optional suffixes
>     'k' or 'K' (kilobyte, 1024), 'M' (megabyte, 1024k), 'G' (gigabyte, 1024M)
>     and T (terabyte, 1024G) are supported. 'b' is ignored.
>   'output_filename' is the destination disk image filename
>   'output_fmt' is the destination format
>   'options' is a comma separated list of format specific options in a
>     name=value format. Use -o ? for an overview of the options supported by the
>     used format
>   '-c' indicates that target image must be compressed (qcow format only)
>   '-u' enables unsafe rebasing. It is assumed that old and new backing file
>        match exactly. The image doesn't need a working backing file before
>        rebasing in this case (useful for renaming the backing file)
>   '-h' with or without a command shows this help and lists the supported formats

^- missing -b

> 
> Parameters to snapshot subcommand:
>   'snapshot' is the name of the snapshot to create, apply or delete
>   '-a' applies a snapshot (revert disk to saved state)
>   '-c' creates a snapshot
>   '-d' deletes a snapshot
>   '-l' lists all snapshots in the given image
> 
> Supported formats: cow qcow vdi vmdk cloop dmg bochs vpc vvfat qcow2 parallels nbd host_cdrom host_floppy host_device raw

Is this intentional? The actual command still works:

> agraf@s390t27:~/git/qemu> qemu-img-kvm create -f qcow2 -b /media/studio/images/SUSE/s390/sles11.raw /dev/shm/sles11-zipl.qcow2
> Formatting '/dev/shm/sles11-zipl.qcow2', fmt=qcow2 size=21474836480 backing_file='/media/studio/images/SUSE/s390/sles11.raw' encryption=off cluster_size=0 


Alex

[Qemu-devel] Re: qemu-img help missing backing file

[Kevin Wolf]

Am 30.03.2010 14:22, schrieb Alexander Graf:
> Howdy,
> 
> I just wanted to create a backed qcow2 image and was irritated by qemu-img not showing me the correct command line option. It's just missing from the list:
[...]
> Is this intentional? The actual command still works:
> 
>> agraf@s390t27:~/git/qemu> qemu-img-kvm create -f qcow2 -b /media/studio/images/SUSE/s390/sles11.raw /dev/shm/sles11-zipl.qcow2
>> Formatting '/dev/shm/sles11-zipl.qcow2', fmt=qcow2 size=21474836480 backing_file='/media/studio/images/SUSE/s390/sles11.raw' encryption=off cluster_size=0 

-b still works to maintain compatibility with older versions. The
documented way is -o backing_file=foo (the qemu-img output you quote
even contains this option).

Kevin

[Qemu-devel] Re: qemu-img help missing backing file

[Alexander Graf]

On 30.03.2010, at 14:30, Kevin Wolf wrote:

> Am 30.03.2010 14:22, schrieb Alexander Graf:
>> Howdy,
>> 
>> I just wanted to create a backed qcow2 image and was irritated by qemu-img not showing me the correct command line option. It's just missing from the list:
> [...]
>> Is this intentional? The actual command still works:
>> 
>>> agraf@s390t27:~/git/qemu> qemu-img-kvm create -f qcow2 -b /media/studio/images/SUSE/s390/sles11.raw /dev/shm/sles11-zipl.qcow2
>>> Formatting '/dev/shm/sles11-zipl.qcow2', fmt=qcow2 size=21474836480 backing_file='/media/studio/images/SUSE/s390/sles11.raw' encryption=off cluster_size=0 
> 
> -b still works to maintain compatibility with older versions. The
> documented way is -o backing_file=foo (the qemu-img output you quote
> even contains this option).

Interesting O_o. Maybe it'd be a good idea to give some examples in the help output? The same way the -e and -b options were having examples there too. That really makes them easier to find.


Alex

[Qemu-devel] Re: qemu-img help missing backing file

[Kevin Wolf]

Am 30.03.2010 14:32, schrieb Alexander Graf:
> 
> On 30.03.2010, at 14:30, Kevin Wolf wrote:
> 
>> Am 30.03.2010 14:22, schrieb Alexander Graf:
>>> Howdy,
>>>
>>> I just wanted to create a backed qcow2 image and was irritated by qemu-img not showing me the correct command line option. It's just missing from the list:
>> [...]
>>> Is this intentional? The actual command still works:
>>>
>>>> agraf@s390t27:~/git/qemu> qemu-img-kvm create -f qcow2 -b /media/studio/images/SUSE/s390/sles11.raw /dev/shm/sles11-zipl.qcow2
>>>> Formatting '/dev/shm/sles11-zipl.qcow2', fmt=qcow2 size=21474836480 backing_file='/media/studio/images/SUSE/s390/sles11.raw' encryption=off cluster_size=0 
>>
>> -b still works to maintain compatibility with older versions. The
>> documented way is -o backing_file=foo (the qemu-img output you quote
>> even contains this option).
> 
> Interesting O_o. Maybe it'd be a good idea to give some examples in the help output? The same way the -e and -b options were having examples there too. That really makes them easier to find.

Feel free to submit a patch. ;-)

Examples sound like an easy way to make these features more visible
again. Even better, but a bit more work, would be to include a
dynamically generated list of all supported options like this:

backing_file: File name of a base image (qcow, qcow2, vmdk)
backing_fmt:  Image format of the base image (qcow2)
encryption:   Encrypt the image (qcow, qcow2)

Kevin

[Qemu-devel] Re: qemu-img help missing backing file

[Juan Quintela]

Kevin Wolf <kwolf@redhat.com> wrote:
> Am 30.03.2010 14:32, schrieb Alexander Graf:
>> 
>> On 30.03.2010, at 14:30, Kevin Wolf wrote:
>> 
>>> Am 30.03.2010 14:22, schrieb Alexander Graf:
>>>> Howdy,
>>>>
>>>> I just wanted to create a backed qcow2 image and was irritated by qemu-img not showing me the correct command line option. It's just missing from the list:
>>> [...]
>>>> Is this intentional? The actual command still works:
>>>>
>>>>> agraf@s390t27:~/git/qemu> qemu-img-kvm create -f qcow2 -b /media/studio/images/SUSE/s390/sles11.raw /dev/shm/sles11-zipl.qcow2
>>>>> Formatting '/dev/shm/sles11-zipl.qcow2', fmt=qcow2 size=21474836480 backing_file='/media/studio/images/SUSE/s390/sles11.raw' encryption=off cluster_size=0 
>>>
>>> -b still works to maintain compatibility with older versions. The
>>> documented way is -o backing_file=foo (the qemu-img output you quote
>>> even contains this option).
>> 
>> Interesting O_o. Maybe it'd be a good idea to give some examples in the help output? The same way the -e and -b options were having examples there too. That really makes them easier to find.
>
> Feel free to submit a patch. ;-)
>
> Examples sound like an easy way to make these features more visible
> again. Even better, but a bit more work, would be to include a
> dynamically generated list of all supported options like this:
>
> backing_file: File name of a base image (qcow, qcow2, vmdk)
> backing_fmt:  Image format of the base image (qcow2)
> encryption:   Encrypt the image (qcow, qcow2)

You can look at how this was done for -cpu

you do -cpu ?model

and it list the models.

Later, Juan.

[Qemu-devel] Re: qemu-img help missing backing file

[Kevin Wolf]

Am 30.03.2010 15:04, schrieb Juan Quintela:
> Kevin Wolf <kwolf@redhat.com> wrote:
>> Am 30.03.2010 14:32, schrieb Alexander Graf:
>>>
>>> On 30.03.2010, at 14:30, Kevin Wolf wrote:
>>>
>>>> Am 30.03.2010 14:22, schrieb Alexander Graf:
>>>>> Howdy,
>>>>>
>>>>> I just wanted to create a backed qcow2 image and was irritated by qemu-img not showing me the correct command line option. It's just missing from the list:
>>>> [...]
>>>>> Is this intentional? The actual command still works:
>>>>>
>>>>>> agraf@s390t27:~/git/qemu> qemu-img-kvm create -f qcow2 -b /media/studio/images/SUSE/s390/sles11.raw /dev/shm/sles11-zipl.qcow2
>>>>>> Formatting '/dev/shm/sles11-zipl.qcow2', fmt=qcow2 size=21474836480 backing_file='/media/studio/images/SUSE/s390/sles11.raw' encryption=off cluster_size=0 
>>>>
>>>> -b still works to maintain compatibility with older versions. The
>>>> documented way is -o backing_file=foo (the qemu-img output you quote
>>>> even contains this option).
>>>
>>> Interesting O_o. Maybe it'd be a good idea to give some examples in the help output? The same way the -e and -b options were having examples there too. That really makes them easier to find.
>>
>> Feel free to submit a patch. ;-)
>>
>> Examples sound like an easy way to make these features more visible
>> again. Even better, but a bit more work, would be to include a
>> dynamically generated list of all supported options like this:
>>
>> backing_file: File name of a base image (qcow, qcow2, vmdk)
>> backing_fmt:  Image format of the base image (qcow2)
>> encryption:   Encrypt the image (qcow, qcow2)
> 
> You can look at how this was done for -cpu
> 
> you do -cpu ?model
> 
> and it list the models.

We do have something like this for block options, -o ? displays this
information - however, it displays them only for a given format, just
like cpu -? displays them only for one architecture.

What is different with my suggestion is that you would iterate over all
image formats and coalesce duplicates into a single line. It shouldn't
be really hard, but a little more work than just changing the help
string to contain some examples.

Kevin