Re: [Qemu-devel] Unmaintained QEMU builds

[Anthony Liguori <anthony@codemonkey.ws>]

On 08/16/2010 01:51 PM, Blue Swirl wrote:
> On Sun, Aug 15, 2010 at 9:42 PM, Anthony Liguori<anthony@codemonkey.ws>  wrote:
>    
>> On 08/11/2010 11:34 AM, Blue Swirl wrote:
>>      
>>> On Wed, Aug 11, 2010 at 10:58 AM, Stefan Weil<weil@mail.berlios.de>
>>>   wrote:
>>>
>>>        
>>>> Hi,
>>>>
>>>> since several months, QEMU for Windows (and mingw32 cross builds)
>>>> no longer builds without error.
>>>>
>>>>          
>>> Not true for mingw32, it was building fine here until the latest commit.
>>>
>>>
>>>        
>>>> I suspect that the same is true for QEMU on Darwin (lots of errors like
>>>> darwin-user/qemu.h:149: error: cast to pointer from integer of different
>>>> size),
>>>> but I'm not sure here because I have no valid Darwin test environment.
>>>> Maybe someone can test this.
>>>>
>>>> What about these environments? They have no maintainers.
>>>> Should they be marked as unsupported? Are they still used?
>>>> Or should they be removed?
>>>>
>>>>          
>>> I compile test mingw32 very often, it's part of my build test setup.
>>> If the build breaks, I may even fix the problem
>>>
>>>        
>> But do you do any testing with the Windows build?
>>      
> Sometime I do a boot test with Wine.
>
>    
>> Historically, even when Windows builds, it spends large periods of time not
>> actually working.  I think Stefan can confirm this.  Much of the platform
>> specific code is way behind (like the block layer) and has been for many
>> years.
>>
>> I can't remember the last time someone sent a Win32 enhancement for platform
>> code.
>>
>> Given that it's known to have a lot of issues, I would suggest that we
>> schedule Windows host support for deprecation in 0.15.  I would not
>> recommend that we remove any of the WIN32 code from the build but basically
>> stop trying to make it even build until someone steps up to really actively
>> maintain and enhance the Windows port.  I would still suggest we take
>> patches if anyone wants to submit them but we should not avoid patches that
>> are known to break win32 (unless the fix is trivial).
>>      
> The same strategy applied to all hosts would probably eventually break
> everything but Linux on x86 with KVM

I don't think that's true but I do agree that we'd lose a lot of 
features.  But if the features aren't being used by anyone and they 
consistently don't work, does it matter?

> . There have been very few patches
> for Darwin, *Solaris, AIX or BSDs, non-x86 targets or non-x86 host
> CPUs. Without Darwin or BSD host support, darwin-user and bsd-user
> will be useless. When did we get Xen patches last time before the
> recent patch set?
>    

Let's put things in perspective though.  Win32 support has been in bad 
shape for years and no one really seems to care.   It's been sorely 
behind since at least when Fabrice introduced AIO support for Linux 
without ever doing it properly in Windows.

TBH, I think dropping kqemu resulted in the last few win32 users moving 
on to something else.

> What about other uncommon and possibly already broken (or never
> finished) features, like Parallels, VVFAT or VMDK support? What about
> new features, do we know in advance that they will be actively
> maintained?
>    

We ought to separately consider features that are isolated and features 
that are invasive.  For something like VMDK or VVFAT, there's very 
little burden that the rest of the code base endures simply by the code 
existing.

Win32 seems to be a constant source of pain though.

> But I'm not completely against this. Maybe we should make a list of
> features and check which of those work. Features which don't pass are
> scheduled for deprecation or removal.
>    

Yes, I think this is exactly what we need to do.

>    
>> For instance, I know that some downstreams (like Android) depend heavily on
>> Win32 so an official statement of deprecation might cause them to push some
>> of their fixes upstream and be more active in upstream maintenance.
>>      
> We haven't received any patches from VirtualBox downstream either, but
> maybe they are still using 0.9.0, so they don't have any.
>    

VBox seems to be a lost cause.  At least the Android folks have 
expressed some willingness to work upstream.

Regards,

Anthony Liguori