Re: [Qemu-devel] [PATCH] Name the default PCI bus "pci.0" on all architectures

[Paul Brook]

> The problem is that the ID names of default devices in machines are ABI
> sensitive. Management apps need to know what the ID of these default
> devices are. The x86 machines have already used 'pci.0' as their name
> in the previous 0.12 release and libvirt is using this naming. We later
> discovered many non-x86 archs have a name of just 'pci'. We need a single
> consistent naming across all arches, hence this patch whcih standardizes
> on 'pci.0'. 

I think you'll find x86 qdev conversion is both incomplete and incorrect.  
Specifically i440fx_int breaks several abstraction boundaries.  I raised this 
issue at the time, but was told this was only temporary, and would be fixed. 
x86 should be made to match the arches that have been converted properly.

> The '.N' convention is used extensively in QEMU and is more
> futureproof as & when QEMU supports multiple buses, without requiring
> apps to use the more verbose device paths to ensure uniquness.

I disagree.  Anything that depends on device creation order is fundamentally 
broken. If you want to create globally unique user-friendly tags for devices 
or busses then that is a completely different problem, and should be done via 
explicit aliases. qemu currently has no concept of a "default bus".

Paul