Re: [Qemu-devel] Re: [PATCH 2/7] Enable I/O thread and VNC threads by default

[Aurelien Jarno]

Anthony Liguori a écrit :
> On 02/08/2011 07:30 AM, Aurelien Jarno wrote:
>> So the strategy is let's break everything and wait for the maintainer to
>> fix that? This strategy doesn't work, we have seen for example that with
>> the SeaBIOS switch. While it brings nice features, it has broken the
>> isapc machine. And it's still not fixed...
>>    
> 
> The fundamental problem is that poorly thought out features have been 
> committed in the past.  isapc is a good example of this.
> 
> You can't just remove a chipset but leave an ISA bus implementation and 
> expect things to just keep working.  Even the early ISA-only systems had 
> a chipset that firmware interfaced with.
> 
>> Also this strategy doesn't scale, then the maintainers are spending
>> their time fixing bugs introduced because others didn't care. Resources
>> are not unlimited, especially for those doing that on their free time.
>>    
> 
> So are you suggesting that every half baked feature should hold up any 
> other future developments?  I think the real problem is exactly the 
> opposite of what you describe.  Why should we waste finite resources 
> keeping something like Windows support limping along?
> 
> We need to do a better job of not adding features that there is no 
> serious intention of every supporting in a meaningful way.  I think the 
> recent discussion of w64 is a good example of this.  I can't imagine 
> trying to support w64 in QEMU until someone actually makes w32 work in a 
> reasonable way.

Yes, we should at least leave people time to find a solution. If nobody
comes with a solution, let's consider it deprecated.

>>> I think we've fixed all that we're aware of but we probably won't find
>>> the rest unless we enable it universally.
>>>      
>> I agree that we are going to discover bugs, and it's normal. QEMU is
>> quite complex and it's not possible to test every combination. That said
>> we are already aware of some bugs, why not fix them, or at least try to
>> fix them? For example we haven't fixed the performance regression with
>> TCG (at least it wasn't the case two weeks ago).
>>    
> 
> If there are known issues, yes, let's fix them before enabling it.
> 

So please look at this TCG performance regression instead of talking
about enabling this just after the release. I don't consider TCG a half
baked feature, for people who forgot about that it's the original QEMU mode.

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net