[Qemu-devel] Re: [PATCH 2 of 5] add can_dma/post_dma for direct IO

[Andrea Arcangeli <aarcange@redhat.com>]

On Sat, Dec 13, 2008 at 10:46:49AM -0600, Anthony Liguori wrote:
> Andrea Arcangeli wrote:
>> On Fri, Dec 12, 2008 at 01:15:13PM -0600, Anthony Liguori wrote:
>>   
>>> void *cpu_physical_memory_map(target_phys_addr_t addr, ram_addr_t size, 
>>> int is_write);
>>>     
>>
>> Just a side note (doesn't mean I agree with the above), it doesn't
>> make sense to use an ram_addr_t size when you return a 32bit address
>> on 32bit qemu build.
>>   
>
> size_t is completely wrong for 64-bit targets on 32-bit hosts.  ram_addr_t 
> is the type we use for guest ram size.  It's 64-bit all of the time simply 
> because it's easier to do that and we decided that the little bit of wasted 
> space/computations were not a problem.

Not sure why you think I'm suggesting you to use size_t. I'm just
trying to tell you that if you insist in this
64bit-guest-on-32bit-host-is-dead-and-obsolete-to-support (i.e. if you
pass a ram_addr_t size to cpu_physical_memory_map) you've at least to
return ram_addr_t too). 'void *' is like size_t so the above API
getting ram_addr_t length and returning 'void *', can't possibly be
sane.