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

[Anthony Liguori]

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.

> > 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.

Regards,

Anthony Liguori