Re: [Qemu-devel] MMIO address changes

[Edgar E. Iglesias]

On Mon, Dec 01, 2008 at 06:59:35PM +0000, Paul Brook wrote:
> I've just committed a patch that changes the MMIO callback interface for 
> devices.  Instead of being passed an absolute address these are now passed an 
> offset from the start[1] of the memory region that was registered.
> 
> By itself this change has fairly neutral benefit, it just moves logic about. 
> However it makes subsequent dynamic board configuration bits nicer, and is a 
> step towards a proper bus level API.
> 
> Most of the groundwork for this is already there, from my earlier changes to 
> separate ram and MMIO addresses TLB handling.
> 
> The main notable change it that the PhysPageDesc structure is not bigger. 
> This 
> isn't ideal, however l2_phys_map needs to go away anyway, so I'm not really 
> worried about this.  
> 
> Some devices register their memory regions in multiple segments. To 
> facilitate 
> this I have added cpu_register_physical_memory_offset.
> 
> Most of the remaining changes are fairly mechanical tweaks to fix devices 
> that 
> explicitly compensated for the absolute address. Many devices are untouched 
> because they ignore the high bits of the address.
> 
> I've tried to be fairly thorough with the changes, and tested what I can. 
> However it's possible I missed or broke something, so please test your 
> favourite targets.

FWIW the etrax-fs machine works OK although I am seeing a noticeable slow-down
after the patch.

Cheers


> 
> Paul
> 
> [1] It's actually the offset from the start of the first page of that region. 
> In practice this difference doesn't matter, and makes the implementation a 
> lot simpler.
>