Re: [Qemu-devel] Re: Compile files only once: some planning

[Anthony Liguori]

On 03/24/2010 05:47 PM, Paul Brook wrote:
> > Actually, Anthony suggested at some point to just use 64 bits for
> > TARGET_PHYS_ADDR_BITS and remove the need for hw32/64.
> >
> > I think that people emulationg 32bits on 32bits would suffer, but have
> > no clue how much.  Anthony, what was the idea?
> >      
> Sacrificing runtime performance to avoid rebuilding a few files is not
> acceptable. I consider the fact that TARGET_PHYS_ADDR_BITS is always 64 on 64-
> bit hosts is a bug. It's just hard to fix, and probably even less of a
> performance hit, so I haven't bothered yet.
>    

It's a statement of correctness really.  Devices should never deal with 
target_phys_addr_t's.

The question is, should a pci_addr_t or a sysbus_addr_t be 64 bit or 
should it be 32-bit on 32-bit platforms.  Honestly, I am extremely 
sceptical that there would be any measurable performance difference.

Regards,

Anthony Liguori

> Paul
>
>
>