Re: [Qemu-devel] [PATCH 1/1] Add -version-simple argument, printing only version number.

[Anthony Liguori <aliguori@linux.vnet.ibm.com>]

On 05/14/2010 05:06 AM, Daniel P. Berrange wrote:
> On Fri, May 14, 2010 at 11:42:57AM +0200, Markus Armbruster wrote:
>    
>> "Daniel P. Berrange"<berrange@redhat.com>  writes:
>>
>>      
>>> On Thu, May 13, 2010 at 10:32:52AM +0200, Jes.Sorensen@redhat.com wrote:
>>>        
>>>> From: Jes Sorensen<Jes.Sorensen@redhat.com>
>>>>
>>>> Add -version-simple argument for QEMU, printing just the version
>>>> number, without any supporting text.
>>>>
>>>> This makes it simpler for other apps, such as libvirt, to parse the
>>>> version string from QEMU independant of how the naming string may
>>>> change.
>>>>
>>>> Signed-off-by: Jes Sorensen<Jes.Sorensen@redhat.com>
>>>> ---
>>>>   qemu-options.hx |    8 ++++++++
>>>>   vl.c            |    9 +++++++++
>>>>   2 files changed, 17 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/qemu-options.hx b/qemu-options.hx
>>>> index 12f6b51..e4f3979 100644
>>>> --- a/qemu-options.hx
>>>> +++ b/qemu-options.hx
>>>> @@ -27,6 +27,14 @@ STEXI
>>>>   Display version information and exit
>>>>   ETEXI
>>>>
>>>> +DEF("version-simple", 0, QEMU_OPTION_version_simple,
>>>> +    "-version-simple display version information and exit\n", QEMU_ARCH_ALL)
>>>> +STEXI
>>>> +@item -version-simple
>>>> +@findex -version-simple
>>>> +Display basic version number information and exit
>>>> +ETEXI
>>>> +
>>>>   DEF("M", HAS_ARG, QEMU_OPTION_M,
>>>>       "-M machine      select emulated machine (-M ? for list)\n", QEMU_ARCH_ALL)
>>>>   STEXI
>>>> diff --git a/vl.c b/vl.c
>>>> index 85bcc84..5adca87 100644
>>>> --- a/vl.c
>>>> +++ b/vl.c
>>>> @@ -2015,6 +2015,11 @@ static void version(void)
>>>>       printf("QEMU emulator version " QEMU_VERSION QEMU_PKGVERSION ", Copyright (c) 2003-2008 Fabrice Bellard\n");
>>>>   }
>>>>
>>>> +static void version_simple(void)
>>>> +{
>>>> +    printf(QEMU_VERSION QEMU_PKGVERSION "\n");
>>>> +}
>>>> +
>>>>   static void help(int exitcode)
>>>>   {
>>>>       const char *options_help =
>>>> @@ -2960,6 +2965,10 @@ int main(int argc, char **argv, char **envp)
>>>>                   version();
>>>>                   exit(0);
>>>>                   break;
>>>> +            case QEMU_OPTION_version_simple:
>>>> +                version_simple();
>>>> +                exit(0);
>>>> +                break;
>>>>               case QEMU_OPTION_m: {
>>>>                   uint64_t value;
>>>>                   char *ptr;
>>>>          
>>> This omits the KVM version string which is something we also want to see.
>>> It would also be nice to avoid having to parse the -help output to determine
>>> ARGV supported too. I wonder if it would be a good idea to just produce a
>>> well structured equivalent to -help that provides the same data, but in
>>> JSON format for sane parsing. That would let peple easily determine the
>>> supported ARGV as well as version number(s)
>>>        
>> I'm all for machine-readable self-documentation.  And the place for that
>> is QMP.  Humble beginnings are already there:
>>
>> { "execute": "query-version", "arguments": { } }
>> -->  {"return": {"qemu": "0.12.50", "package": ""}}
>>
>> { "execute": "query-commands", "arguments": { } }
>> -->  {"return": [{"name": "quit"}, {"name": "eject"}, [...]
>>
>> Any practical problems with use of QMP instead of parsing command line
>> option output?
>>      
> It is unneccessarily complex for such a simple task, requiring you to
> configure&  connect to the monitor&  do the capabilities negotiaton
> and then issue the command.
>
> To just query the version requires this ridiculous interaction:
>
>    $ qemu -chardev stdio,id=monitor -monitor chardev=monitor,mode=control
>    {"execute":"qmp_capabilities"}
>    {"QMP": {"version": {"qemu": "0.12.1", "package": " (qemu-kvm-0.12.1.2)"}, "capabilities": []}}
>    {"execute":"query-version"}
>    {"return": {"qemu": "0.12.50", "package": ""}}
>
>
> I'm suggesting we just allow some simple syntactic sugar on the command
> line for the handful of QMP commands that are just returning static info
> about the binary, that are not affected by VM state.
>
> eg, make this work:
>
>    $ qemu -query-version
>    {"qemu": "0.12.50", "package": ""}
>    

No need for package.  Vendors can use vendor extensions to add whatever 
info they want.

But we should avoid an encoded string, it would be better as:

{"major": 0, "minor": 12, "release": 50}

And then it could be:

{"major": 0, "minor": 12, "release": 50, "__org.linux-kvm.release": 1, 
"__com.redhat.RHEL6.release": 13}

We could also just pretty print it:

major: 0
minor: 12
release: 50
__org.linux-kvm.release: 1
__com.redhat.RHEL6.release: 13

Regards,

Anthony Liguori

> Daniel
>