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Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help
From: |
Cole Robinson |
Subject: |
Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help |
Date: |
Tue, 27 Jul 2010 09:35:55 -0400 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.11) Gecko/20100720 Fedora/3.0.6-1.fc12 Thunderbird/3.0.6 |
On 07/27/2010 08:50 AM, Anthony Liguori wrote:
> On 07/27/2010 07:30 AM, Cole Robinson wrote:
>> On 07/27/2010 05:47 AM, Jes Sorensen wrote:
>>
>>> On 07/27/10 10:11, Markus Armbruster wrote:
>>>
>>>> Anthony Liguori<address@hidden> writes:
>>>>
>>>>> On 07/26/2010 02:19 PM, Avi Kivity wrote:
>>>>>
>>>>>> We should try to support all users, prioritized by the number of end
>>>>>> users they represent. If this patch broke some other large user
>>>>>> we'd be in a bind. But likely this isn't the case so we aren't.
>>>>>>
>>>>> As I've said, I'm pragmatic and that's why I've argued for these
>>>>> changes in the past. But libvirt should have changed a long time ago
>>>>> to using something more reliable (like version).
>>>>>
>>>> You want pragmatic? I can give you pragmatic! We apply the trivial
>>>> patch that helps libvirt and hurts nobody, and save our breath& typing
>>>> for designing and implementing a capability system.
>>>>
>>> To be honest, this is exactly the same problem we had when the output
>>> from -version changed and libvirt broke because it did static string
>>> parsing instead of doing it properly. Back then the output of -version
>>> was changed back to accommodate libvirt, but I am not aware that libvirt
>>> went ahead and fixed the real problem in the mean time.
>>>
>>>
>> The output of -version was not changed back, the revert was rejected.
>> (Meaning QEMU has no stable interface for determining version info.
>>
>
> Actually, we do. 'info version' in the monitor returns just the version.
>
My bad, I didn't know about that. Then again, having to start up a qemu
instance and connect to the monitor just to get a bare version string
seems overkill.
> Additionally, -version on the command line spits out just a single
> version string.
>
I wouldn't really call that 'stable', figuring that the output was
changed recently.
> The trouble libvirt has is that it's parsing the help output and needs
> to use a string to identify which line is the version (due to the way
> it's parsing the output).
>
> Notice a theme here?
>
A few: libvirt's -help parsing is fragile. Libvirt is using an
unsupported/unstable capabilities system, though it works acceptably in
practice.
Some others: Libvirt is a significant qemu consumer and provides value
to the qemu project. qemu lacks a supported discoverable capabilities
interface.
And some facts: qemu 0.13 will not work with 95% of existing libvirt
deployments. The 2 requested qemu reverts will have approx. 0 functional
impact on plain qemu users.
Can we evaluate these all together? Really, what's the harm in reverting
these changes for 0.13, reapplying after the release is cut, and making
a commitment to get some capabilities interface into 0.14? (and no
libvirt appeasing -help/-version patches in the 0.14 cycle)
- Cole
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, (continued)
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Avi Kivity, 2010/07/26
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Anthony Liguori, 2010/07/26
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Avi Kivity, 2010/07/26
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Anthony Liguori, 2010/07/26
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Avi Kivity, 2010/07/26
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Anthony Liguori, 2010/07/26
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Markus Armbruster, 2010/07/27
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Jes Sorensen, 2010/07/27
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Cole Robinson, 2010/07/27
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Anthony Liguori, 2010/07/27
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help,
Cole Robinson <=
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Markus Armbruster, 2010/07/27
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Avi Kivity, 2010/07/26
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Anthony Liguori, 2010/07/26
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Avi Kivity, 2010/07/26
- [Qemu-devel] Re: [PATCH] move 'unsafe' to end of caching modes in help, Juan Quintela, 2010/07/26
- Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Kevin Wolf, 2010/07/27
Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Luiz Capitulino, 2010/07/22
Re: [Qemu-devel] [PATCH] move 'unsafe' to end of caching modes in help, Daniel P. Berrange, 2010/07/27