Re: [Qemu-devel] [PATCH 0/7] poison TARGET_xxx for compile once object and header file cleanups

[Paolo Bonzini]

On 06/27/2010 09:32 PM, Blue Swirl wrote:
>  From just clean up or type safety point of view, this is good stuff.
> But from architectural point of view, we should make it more difficult
> to use CPUState in device code, not easier. This may still be fine as
> a temporary measure, before all CPUState references have been removed.

I don't see it at all as a temporary measure.  In theory, only devices 
compiled per-target would need access to CPUState, that's true. 
However, there are conflicting goals which make an opaque CPUState 
preferrable.

First, converting devices such as APIC to qdev requires knowledge of 
CPUState in qdev, unless you want to keep DEFINE_PROP_PTR (whose removal 
is much more interesting) or sweep it under the void* blanket.  PICs are 
likely to have CPUState members, e.g. hw/pxa2xx_pic.c (and BTW indirect 
access via functions to these fields is making emulation a little bit 
slower).

Also, for things compiled in libhw that are not part of device code, 
requiring knowledge of CPUState is absolutely not problematic and the 
only alternative loses type-safety and so it is inferior.

Paolo