Re: [Qemu-devel] [PATCH 2/2 v2][UPDATED] Direct IDE I/O

[Avi Kivity <avi@qumranet.com>]

Paul Brook wrote:
>> Unfortunately it is more complicated to write to the CPU memory. In
>> particular, specific action should be done when translated code is
>> present. A consistent API must include something like cpu_page_lock() /
>> unlock(). Look at cpu_physical_memory_rw() to see the various issues
>> which must be handled. Moreover, it would be better to add bus specific
>> APIs (at least for PCI), but I can accept a CPU memory API for now.
>>     
>
> In general it may also be unsafe to do async writes directly to guest memory 
> because you break the atomicity of loads/stores.
>
>   

But that is true on real hardware as well, I think.  The guest cannot 
expect atomicity if it dmas into the memory it is accessing.

Also, it would be a rare guest that accesses memory while dma is active.

-- 
error compiling committee.c: too many arguments to function