Re: [Qemu-devel] [4261] Errors while registering ioports are not fatal (Glauber Costa).

[Anthony Liguori]

Paul Brook wrote:
> On Saturday 26 April 2008, andrzej zaborowski wrote:
>   
> > On 26/04/2008, Paul Brook <address@hidden> wrote:
> >     
> > > On Saturday 26 April 2008, Andrzej Zaborowski wrote:
> > >  > Revision: 4261
> > >  >          
> > >  > http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=4261 Author:
> > >  >   balrog
> > >  > Date:     2008-04-26 16:04:29 +0000 (Sat, 26 Apr 2008)
> > >  >
> > >  > Log Message:
> > >  > -----------
> > >  > Errors while registering ioports are not fatal (Glauber Costa).
> > >
> > >  Why shouldn't they be fatal? How can this be anything other than a
> > > serious bug in the device emulation?
> > >       
> > This change is perhaps not useful, it would be useful with hot-plugged
> > / proxied pci devices.  
> >     
>
> I fail to see how hotplugging or proxing has anything to do with it. IO port 
> registration is not something that can reasonably fail.
>
> If the real problem is that we can't cope with multiple devices registering 
> the same IO port than you need to fix that. Blindly punting to the caller to 
>   

There is no fix for that.  You can't have two devices that use the same 
IO port.

> cope is IMHO not an acceptable solution, especially when none of the callers 
> check the return value.
>   

IO port range conflicts can still happen even with PCI devices.  Two PCI 
IDE controllers would conflict with each other for instance.  It's much 
more likely with ISA of course but it's still possible.  register_ioport 
really should have a return code and callers should actively be checking it.

Regards,

Anthony Liguori

> Paul
>
>
>