Re: [Qemu-devel] Re: [PATCHv2] qemu: target library, use it in msix

[Michael S. Tsirkin]

On Sun, Sep 27, 2009 at 04:14:49PM +0200, Avi Kivity wrote:
> On 09/27/2009 04:08 PM, Michael S. Tsirkin wrote:
>>
>>    
>>>> In practice, the only user is now msix and it does not.  It has 0x1000
>>>> as a constant parameter.  For target_phys_addr_t users if we ever have
>>>> them, we'll just add target_phys_page_align. Generally it's unusual for
>>>> devices to care about size of target physical page.
>>>>
>>>>        
>>> I'd fill better with uint64_t, at least that won't truncate.
>>>      
>> Doesn't naming it target_page_align32 address this concern?
>>    
>
> How can the caller (except in your special case) know if it has a  
> quantity that will fit in 32 bits?

It's actually not unusual for devices to limit addressing to 32 bit, whatever
the bus supports.  For example, the value might come from a 32 bit pci
bar, even on a 64 bit system this will get values 0 to 4G.

>
> -- 
> Do not meddle in the internals of kernels, for they are subtle and quick to 
> panic.