Re: [Qemu-devel] [PATCH v2 1/2] console: add hw_screen_dump_async

[Avi Kivity <avi@redhat.com>]

On 03/05/2012 08:16 PM, Anthony Liguori wrote:
>
>>
>>>    We're pretty close to being there.  Luiz, about how long do you
>>> think before we get there?
>>
>> It's a pity to add new commands along the way.
>
> It's more complicated than this unfortunately.
>
> A client needs to be able to determine whether the 'screendump'
> command works as expected.  Unfortunately, when QXL was introduced,
> 'screendump' became broken across multiple releases.
>
> screendump is the right interface, but since it was broken in multiple
> releases, we need another command for a client to determine that it's
> not broken.  In the short term, screendump_async is that.  After QAPI,
> it will probably be a screendump2.
>
> I don't mind introducing short term commands and then deprecating it
> particularly when they are marked as such.

Zooming out from screendump, there are several ways to deal with broken
commands:

1. introduce new commands
2. introduce capabilities that say "screendump is fixed wrt bug so-and-so"
3. fix it and backport the fix to a stable release
4. ignore the broken command and hope

My preference is 3->2->1->4, or we'll end up with screendump65535 soon.

-- 
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